What air cooler to get for 3950x? I don't want water cooling.

kamikazi

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Ludicrous, untrue, and unsubstantiated nonsense in that order. And I'll prove it.

Before the days of boost clocks, a CPU's clock speed was a set value from the factory. If you had a Pentium 200MHz processor, then you could easily measure the cooling solution by your CPU temps and that's all you needed to do. When loaded, the CPU's clocks were a fixed value. Even when overclocking, older CPU's still had a fixed maximum clock speed and once your cooling could no longer extend the clocks, you were at a point where you could determine which cooling solutions were good enough or could be considered overkill. These days, clock speeds are dynamic. A CPU no longer has a set clock speed value. Instead, you are given a base clock as a minimum standard of what you can expect under load. Then, you are given a boost clock value which is what the CPU can achieve under certain ideal conditions. There are no guarantees you'll ever see these clock speed values nor are there stipulations on how long the CPU will hold that value or even any guarantees on precise conditions which will result in a given clock speed. We do know how to trigger these conditions for test purposes but there are a lot of variables here and what you get varies by individual configuration and even by specific CPU.

Your CPU's boost clock behavior is determined by a number of factors. EDC, PPT, and TDC. They are electrical design current, power package tracking and thermal design current. One additional factor is CPU temperature. If you hit the limits, it will drop the clocks to a lower range to reduce not just temperatures, but in order to keep EDC, PPT and TDC within a certain operational range. It is important to note that the EDC, PPT and TDC values are set by AMD at the factory for these CPU's. There are stock values and precision boost 2 values. The latter obviously are more generous and allow the CPU to reach higher clocks conditions permitting. Precision Boost Overdrive overrides these values and uses motherboard manufacturer specified values.

View attachment 213897

On my test bench right now, at default settings, the 3950X test chip operates in similar temperature ranges. I'm seeing temperatures around 55-58c. I'm getting 3.95-4.0GHz clock speeds running Cinebench or other multithreaded workloads. EDC is at 97%, TDC and PPT are at 100%. These are limits defined by AMD. This isn't PB2, or PBO mind you. These values are more conservative keeping the PPT, EDC and TDC as my limiting factors. As a result, temperature isn't a limitation here. Therefore, my CPU's clocks are limited by those values I keep mentioning. AMD's stock values are conservative and it allows the CPU to operate on virtually any motherboard and with a modest cooling solution. These values keep the temps down and like this, yes, a 240mm AIO would suffice. That said, the CPU is capable of more than the above. So in this scenario we are leaving performance on the table and not getting the most out of our 3950X.

View attachment 213892

Using PB2, higher values are allowed for TDC, EDC and PPT. Using custom water, I'm at 76.11c or thereabouts, but my clock speeds have now reached 4.12GHz to 4.15GHz running Cinebench. If that's what I'm getting on custom water, your 240mm AIO would be out of headroom. Your temps would likely be in the 85c range or worse. Is that doable? Maybe, but I'm not sure that your clocks would actually be as high running that cooler. They certainly aren't running high end air cooling as others in this thread have mentioned. Some have mentioned getting only around 3.9GHz on high end air cooling. These clock speed differences might not seem like much, but Zen 2 scales very well with clock speed increases. Unfortunately, the architecture doesn't have much headroom left in it, which is why we aren't seeing clocks that look more like Intel's. We know from looking at single threaded applications and confirming boost clocks that these micro bursts into the 4.4-4.7GHz range allow the Ryzen 3000 series to be more competitive and even faster than Intel in some cases. Keep in mind, that single-threaded performance is where Intel still does quite well.

View attachment 213894

Under Precision Boost Overdrive, or PBO, we see some differences in performance. Our clocks are actually slightly lower and the CPU temperatures are essentially the same. Thus, our limitations are something else. This has always been the case with the upper end Ryzen 3000 series CPU's. What it seems like is that the clocks are held longer, even if they are a bit lower. This doesn't always result in a boost in performance either and as such PB2 is generally the better option over the supposedly more aggressive PBO which worked well on second generation CPU's like the Ryzen Threadripper 2920X.

View attachment 213895

Now, we are on full manual control. Our voltage is locked in and our CPU clocks are set to 4.3GHz. All the cores are set the same and I repeated the Cinebench R20 run. This was taken near the end of the run, so the temps are at their highest. I will say that I've seen worse temps on this configuration, but it's cooler today than it was the other day when I tested this. But, as you can see the slight increase in clock speeds has resulted in a slight increase in temperatures. Running all core overclocks on these things produces much higher than normal temperatures. It's not usually worth doing and while temps do play a part in our limitations here, simply not seeing high temperatures doesn't mean that your cooling is adequate. It might be adequate without PB2 or PBO running. Or, it could mean that other limitations are in place keeping your clocks down so you aren't seeing your thermal limitations.

I don't have a high end air cooler on hand or I'd have tested it. But based on the data I've seen and shared here, there is virtually no chance that you aren't leaving at least some performance on the table by opting for air cooling instead of a high end 360mm AIO at the very least. Custom water cooling will produce better results. Given the cost of building a good water cooling setup, I can see why some people would be hesitant to go that route despite spending $750 on a CPU. A good setup is going to be at least $400-$500 and it does require more maintenance to deal with and more skill to put it together. First timers will waste more money than they need to by not accounting for every fitting, length of tubing, or flat cutting tubing wrong or whatever. They might need a different case or have to buy some tools to get the job done.

All that said, I stand by my assertion that high end air cooling isn't enough to tame a 3950X and get the most out of it. I think I've shown enough data to prove it as well. Furthermore, if your really feeling up to it, let's try an experiment: If you really think your cooling solution is up to the task, try a 4.3GHz manual overclock on all cores and run Blender bench or Gooseberry and then tell me what your temperatures are. As you can see, at 4.3GHz all core I'm at 79c on custom water cooling doing a quick Cinebench run. I'm using a Koolance Exos 2.5 (360mm radiator) and an Alphacool Eisblock water block. This specific test represents both a heavily multithreaded workload and it represents the edge of what these chips can typically do with a manual all core overclock. If your cooling solution can handle 4.3GHz all core doing something like Prime95, Blender, Gooseberry, etc. then its probably good enough.

I'm just using Cinebench here. This is quick and dirty. When you load up something like Gooseberry, you'll quickly see your cooling solutions limitations. Using this, I'll hit 85c by the end of the hour long run at a 4.3GHz all core overclock. Doing that, you'll likely overrun a 240mm AIO and an air cooler would have NO chance of getting through the test.

Again, AMD doesn't recommend air cooling for the 3950X and doesn't include one with it. Looking at the temps, clocks and real world power consumption, its easy to see why.
Thanks for your very informative post. Now, I just have to look into making PB2 work on my system.
 

Dan_D

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Thanks for your very informative post. Now, I just have to look into making PB2 work on my system.
As stated before, it should be on by default. My test system does boost but behaved better when I specifically turn it on in Ryzen Master.
 

thesmokingman

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I haven't ever tried setting fan curves based on coolant temp. The cpu temp would be way too high if I did. Maybe I'll look at it again. Right now, I have pretty aggressive curves based on core temp, but the 3950x only boosts to around 3900 MHz in CB20.
It's quite normal to base cooling on water delta. This is especially important when you have instances where the gpu/s are loaded and cpu is not. If your cpu temp is too high, chances are so is your water temp. If not than all the heat is isolated to your cpu block, meaning you have issues transferring that heat. The 3970x I just built is monitored off of water temp, and that loop maintains a 10c delta.

Btw, 20c ambient is pretty damn cold. That's why his temps look better, he lives in a fridge.
 
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Dan_D

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I think I'm getting that same behavior.
It's pretty common unfortunately. I don't recall ever seeing that with the ASUS Crosshair VIII Hero, but the MSI MEG X570 GODLIKE has done it pretty consistently since launch.
 

bobzdar

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It's quite normal to base cooling on water delta. This is especially important when you have instances where the gpu/s are loaded and cpu is not. If your cpu temp is too high, chances are so is your water temp. If not than all the heat is isolated to your cpu block, meaning you have issues transferring that heat. The 3970x I just built is monitored off of water temp, and that loop maintains a 10c delta.

Btw, 20c ambient is pretty damn cold. That's why his temps look better, he lives in a fridge.
20C is 68F, that's not cold. It is winter here and I have the heat set to 65F in the house but It's warmer in the room the pc is in, probably 70-72F, case temp of 30C is fairly accurate based on temp sensors on the mobo. It goes up in lock step with coolant temp. My rad does not pull directly from outside, so it's getting a mix of case and fresh air. Not ideal but as good as I could manage with my case and enough to keep things cool.
 

Jamie Marsala

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I just find it crazy that someone will spend $750 on a CPU then skimp on keeping it as cool as possible so that it performs the best it can. I only have a 3900x but I can tell you sure the stock cooler that came with it is fine and even the D15 did fine but it does a hell of a lot better and consistently with an AIO, so I assume the 3950 would behave better with the added cooling. Personally I did not spend $500 for the best AMD Proc out at the time for it to not run at its peak performance. But whatever, it is your money.
 

Furious_Styles

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I just find it crazy that someone will spend $750 on a CPU then skimp on keeping it as cool as possible so that it performs the best it can. I only have a 3900x but I can tell you sure the stock cooler that came with it is fine and even the D15 did fine but it does a hell of a lot better and consistently with an AIO, so I assume the 3950 would behave better with the added cooling. Personally I did not spend $500 for the best AMD Proc out at the time for it to not run at its peak performance. But whatever, it is your money.
You can buy a $450-500 9900k and cool it @ stock clocks with a cheap $30 212 evo.
 

DogsofJune

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You don't buy a 9900k and run it at stock clocks.
Where is the fun in that expense? ;)
 

kamikazi

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It's pretty common unfortunately. I don't recall ever seeing that with the ASUS Crosshair VIII Hero, but the MSI MEG X570 GODLIKE has done it pretty consistently since launch.
I've done manual overclocking in Ryzen Master, but I'm not sure on how to verify that PB2 is working in there. I hope to look at it tonight. Any tips?
 

Dan_D

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I've done manual overclocking in Ryzen Master, but I'm not sure on how to verify that PB2 is working in there. I hope to look at it tonight. Any tips?
Just enable automatic overclocking in one of the profiles. It will prompt for a restart. When you get back into the OS, simply enable this again in the profile and it will run in auto-overclocking mode which is PB2.

Running with default settings on the motherboard (minus enabling XMP), I saw clock speeds of 3.9-4.0GHz in multithreaded workloads. Using auto-overclocking within Ryzen Master got me up to 4.1-4.15GHz in the same workloads. Temps were much better using the motherboard settings, but the performance was definitely worse.
 

kamikazi

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Just enable automatic overclocking in one of the profiles. It will prompt for a restart. When you get back into the OS, simply enable this again in the profile and it will run in auto-overclocking mode which is PB2.

Running with default settings on the motherboard (minus enabling XMP), I saw clock speeds of 3.9-4.0GHz in multithreaded workloads. Using auto-overclocking within Ryzen Master got me up to 4.1-4.15GHz in the same workloads. Temps were much better using the motherboard settings, but the performance was definitely worse.
Thanks for the info. I think I actually may have enabled auto overclocking on the 3900x I had at some point. I didn't realize that was PB2. It definitely ran faster, but I don't remember to what degree. It really seems like you should be able to do that in the BIOS alone doesn't it. With the RAM I have, I can't run XMP and I've changed a lot of settings to get that stable including setting the fclk manually. I wonder if some of that contributes to PB2 not working as advertised. CB20 runs currently hover around 3900 MHz with temps in the 60s. However, I get spikes up to 75 or so that I never see happen in realtime, they just show up in the max temp.
 

kamikazi

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20C is 68F, that's not cold. It is winter here and I have the heat set to 65F in the house but It's warmer in the room the pc is in, probably 70-72F, case temp of 30C is fairly accurate based on temp sensors on the mobo. It goes up in lock step with coolant temp. My rad does not pull directly from outside, so it's getting a mix of case and fresh air. Not ideal but as good as I could manage with my case and enough to keep things cool.
You must be living right. Sounds like you have very nice temps given the setup.
 

Furious_Styles

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And it will be comprehensively outclassed when under the types of loads that make this kind of cooling necessary. It's apples and oranges.
I've got a feeling you could do 5ghz all core on the evo. Or you could buy a H150i and have cooler temps and maybe get to 5.2-5.2ghz. For clarity my post is not comparing it to a 3950x, it is that you don't have to spend crazy amounts to get excellent performance.
 

BrotherMichigan

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I've got a feeling you could do 5ghz all core on the evo. Or you could buy a H150i and have cooler temps and maybe get to 5.2-5.2ghz. For clarity my post is not comparing it to a 3950x, it is that you don't have to spend crazy amounts to get excellent performance.
I feel like you're in the wrong thread then.
 
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Furious_Styles

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I feel like you're in the wrong thread then.
Look, Dan is 100% correct in saying if you want to get everything out of the 3950x you go open loop. But as he also stated that is pretty damn expensive and not simple if you've never done it before. But here is the title of the thread: what-air-cooler-to-get-for-3950x-i-dont-want-water-cooling. So no, I don't think I'm in the wrong thread.
 

RavinDJ

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AMD Ryzen 9 3950X 16-core, 32-thread Unlocked Desktop Processor ordered.
MSI MEG X570 GODLIKE Motherboard ordered.
Lian Li O11 Dynamic XL (White) Full Tower Gaming Computer Case ordered.
CORSAIR iCUE H150i RGB PRO XT, 360mm Radiator Liquid CPU Cooler ordered.

All I need now is DDR4 memory and an M.2 SSD and a PSU.

I cannot thank you enough guys. This is my first build since a very, very, very, very long time ago. It will last me a looooooong time.
Hey guys... I know it's AMD forum and all... but, since I'm the OP :)

What PSU/RAM/GPU should I match to the above?
 

thesmokingman

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Check the hot deals forum, there's decent memory on sale for 99, get two packs of that. Psu wise, anything efficient 600-800w is more than enough, unless you go with a big gpu then add another 100w. Gpu depends on what yer gonna do with it.
 

RavinDJ

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Check the hot deals forum, there's decent memory on sale for 99, get two packs of that. Psu wise, anything efficient 600-800w is more than enough, unless you go with a big gpu then add another 100w. Gpu depends on what yer gonna do with it.
Just want to power 3 monitors and a 42" TV with HDMI. No crazy gaming; no crazy overclocking; just be able to view as many screens at a time as possible. Is 4 screens max? 5? on a single GPU, that is. No SLI or multi-GPU for me yet.
 

thesmokingman

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Just want to power 3 monitors and a 42" TV with HDMI. No crazy gaming; no crazy overclocking; just be able to view as many screens at a time as possible. Is 4 screens max? 5? on a single GPU, that is. No SLI or multi-GPU for me yet.
What ports? Check newegg, they have great filters.
 

thesmokingman

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Yer not going to find anything with that many hdmi ports. You should look to replacing those with dp panels in the future. For now I see dp to hdmi converters in your near future, lol.
 

kamikazi

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I'm liking my Seasonic Prime Gold PSU so far. The Seasonic Focus Plus Gold is also a great power supply and more compact if that's what you need. If you're not going big on the GPU, you could get a 650 watt and you'd be covered. FWIW, I measured my old system (Intel 2700k @ 4.5 GHz and 1080 Ti with a couple of hard drives and lots of fans) running Prime 95 and a loop of Heaven at the same time with a Kill-A-Watt meter and it was right at 500 watts. The only problem I see is that everything appears out of stock right now. The best buy of the bunch is the Prime Gold 850 for $145.00 at Amazon. You don't seem to get much of a discount with lower wattage units. As for RAM, look at the QVL of the motherboard and pick some DDR4 3600 that is supported. Apparently it does make a difference if it's on the QVL.
 

stormlight

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I have a Noctua D15 (only 1 middle fan) with 3900X and was getting constant 200W (206W peak) package power at stock votlage of 1.48V(Auto). Prime95/OCCT does not stress CPU adequately. I had to use two running instances of Handbrake to max cpu utlization power. The cpu stayed around 80C with fan speed at ~1250rpm. I have since undervolt it with offset of -.1V. The package drops about about 20% is power: constant ~160W on package (~170W peak) (PPT+ ~30W L-Caches). Use HWinfo or HWmonitor, it will tell you package power. My temperature is now 76C at 1100rpm. My room ambient temperature is 74F.

If I scale the 3950X correctly, 3950X with undervolt (-.1V offset/1.38V) should yield around 208W constant power. The Noctua D15 can easily keep the cpu around 80C with ~1250rpm. There is alot more overhead for additional cooling from the fan thus I see 3950X is within limit for Noctua D15. You can max out the fan rpm and it probably drop the temp another 10C. This is the setup with 1 middle fan. I have the 2nd fan too but it is not need for me at this time. I am more focus on quietness. If I have to guess, my system would be around 25dB: I can barely hear the cpu fan 3 feet away.

If you are undervolting, please make sure to use Cinebench R20 to verify performance is not degraded. Run both the MP and Single Core bench. Beyond -.1V offset, I get single core degradation. The single core will get affect much sooner than multi-core bench. You need the higher voltage for higher frequency switching.
 
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bobzdar

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I have a Noctua D15 (only 1 middle fan) with 3900X and was getting constant 200W (206W peak) package power at stock votlage of 1.48V(Auto). Prime95/OCCT does not stress CPU adequately. I had to use two running instances of Handbrake to max cpu utlization power. The cpu stayed around 80C with fan speed at ~1250rpm. I have since undervolt it with offset of -.1V. The package drops about about 20% is power: constant ~160W on package (~170W peak) (PPT+ ~30W L-Caches). Use HWinfo or HWmonitor, it will tell you package power. My temperature is now 76C at 1100rpm. My room ambient temperature is 74F.

If I scale the 3950X correctly, 3950X with undervolt (-.1V offset/1.38V) should yield around 208W constant power. The Noctua D15 can easily keep the cpu around 80C with ~1250rpm. There is alot more overhead for additional cooling from the fan thus I see 3950X is within limit for Noctua D15. You can max out the fan rpm and it probably drop the temp another 10C. This is the setup with 1 middle fan. I have the 2nd fan too but it is not need for me at this time. I am more focus on quietness. If I have to guess, my system would be around 25dB: I can barely hear the cpu fan 3 feet away.

If you are undervolting, please make sure to use Cinebench R20 to verify performance is not degraded. Run both the MP and Single Core bench. Beyond -.1V offset, I get single core degradation. The single core will get affect much sooner than multi-core bench. You need the higher voltage for higher frequency switching.
3950x uses the same power as the 3900x...
 

stormlight

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3950x uses the same power as the 3900x...
According to the screen shot from Dan_D, it uses more power. PPT was at 205W + ~40W (larger L-Cache) = ~245W package. I was guessing around ~260W package power in my math for scaling. I am not sure on the thread count of handbrakes, but do 2-3 instance of handbrake in parallel and you will see the true power usage. It is insane! I know the TDP is 108W for both 3900x and 3950x, but we have unlocked this limited at the Mobo. The remainder limits are on-cpu fused limit, board new power limit, and thermal limit. Most probably would hit EDC limit after power limit but you can negate that by increasing VCore but it will run hotter.

To be honest, these CPU are way underrated for their power usage, 3900x@4.1GHZ all core it should be rated for 206W@1.48V (Auto). I am not overclocking too but within boost limit (constant boost)! IMO, most programs cannot take advantage of this at the moment unless you run few of them in parallel. If you leave at mobo setting at stock, you will see PPT stuck at 100% which is core power limited.

Another note to add is: 1 handbrake instance: I have an average around 28FPS. 2 handbrake instances: I have an average combined of 36fps.
 
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Dan_D

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3950x uses the same power as the 3900x...
This only applies to the 3950X and the 3900X

Not when being overclocked.
Indeed. Power consumption shoots through the roof when you compare the two. In fact, I have a graph for that:

upload_2020-1-8_21-56-17.png


As you can see, using the exact same configuration, the 3950X pulls just a few watts more under load at stock speeds. This really isn't all that bad, but it does pull more power. BTW, this isn't even close to AMD's reported 105w TDP. The video card is basically idle here as this is done using Cinebench's multi-thread test.


upload_2020-1-8_21-57-10.png


Overclocked, we can see a significant increase in wattage. The 3950X pulls about 50 watts more at the same clock speed. Overclocked values are done with all cores set to run at 4.3GHz on both processors.
 

kamikazi

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I got some more testing done tonight. Strange behavior though. When I booted up my computer, it wouldn't post and I eventually had to clear CMOS and start over. I loaded the same profile that was on it yesterday and now single core on the cpu just doesn't work as well. Boost tester shows weaker results with no core exceeding 4600 MHz. Yesterday, the entire good chiplet could boost over 4600 with several close to 4700. CB20 single core dropped from 528 to 509. Multicore also scores under 9000 with cpu clocking under 3900 MHz.

2020-01-09 00.49.12.jpg

See above that PB2 is broken. Running CB20 multi with temps at 61C, only getting 3838 MHz. This should boost higher, no? The only tweaks I've made in BIOS are memory settings. Everything else is stock. When I enable PB2 in Ryzen Master, I get the same results as default. The same power limits are in place. I can, however manually boost the power limits with PBO in BIOS and get some improvements. Then, in Ryzen Master, I can enable PB2, and it works. I can score just over 9300 in CB20 multi. Clock speed tends to hover around 4050 MHz. Temps hit the low 80s. I don't think I can get much more out of it. I haven't tried any all core overclocking, but my current cooler is not going to do much more. I'm a bit disappointed. I really thought I should be boosting around 4000 default and 4100 with PB2. Right now, it appears 4050 is my limit with PBO.
 
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Dan_D

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I got some more testing done tonight. Strange behavior though. When I booted up my computer, it wouldn't post and I eventually had to clear CMOS and start over. I loaded the same profile that was on it yesterday and now single core on the cpu just doesn't work as well. Boost tester shows weaker results with no core exceeding 4600 MHz. Yesterday, the entire good chiplet could boost over 4600 with several close to 4700. CB20 single core dropped from 528 to 509. Multicore also scores under 9000 with cpu clocking under 3900 MHz.

View attachment 214357

See above that PB2 is broken. Running CB20 multi with temps at 61C, only getting 3838 MHz. This should boost higher, no? The only tweaks I've made in BIOS are memory settings. Everything else is stock. When I enable PB2 in Ryzen Master, I get the same results as default. The same power limits are in place. I can, however manually boost the power limits with PBO in BIOS and get some improvements. Then, in Ryzen Master, I can enable PB2, and it works. I can score just over 9300 in CB20 multi. Clock speed tends to hover around 4050 MHz. Temps hit the low 80s. I don't think I can get much more out of it. I haven't tried any all core overclocking, but my current cooler is not going to do much more. I'm a bit disappointed. I really thought I should be boosting around 4000 default and 4100 with PB2. Right now, it appears 4050 is my limit with PBO.
Actually, if your signature is correct on your cooling, you are getting roughly what I'd expect. That's also in line with what others are seeing. What surprises me is that PBO would do anything for you as it achieved worse results in my experience. Under full load I can hit 80-85c on my test CPU, except that I'm on custom water and my clocks are higher. I'm at 4.1GHz to 4.15GHz with PB2 enabled. PBO was worse coming in at 3.9-4.0GHz.
 

bobzdar

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I got some more testing done tonight. Strange behavior though. When I booted up my computer, it wouldn't post and I eventually had to clear CMOS and start over. I loaded the same profile that was on it yesterday and now single core on the cpu just doesn't work as well. Boost tester shows weaker results with no core exceeding 4600 MHz. Yesterday, the entire good chiplet could boost over 4600 with several close to 4700. CB20 single core dropped from 528 to 509. Multicore also scores under 9000 with cpu clocking under 3900 MHz.

View attachment 214357

See above that PB2 is broken. Running CB20 multi with temps at 61C, only getting 3838 MHz. This should boost higher, no? The only tweaks I've made in BIOS are memory settings. Everything else is stock. When I enable PB2 in Ryzen Master, I get the same results as default. The same power limits are in place. I can, however manually boost the power limits with PBO in BIOS and get some improvements. Then, in Ryzen Master, I can enable PB2, and it works. I can score just over 9300 in CB20 multi. Clock speed tends to hover around 4050 MHz. Temps hit the low 80s. I don't think I can get much more out of it. I haven't tried any all core overclocking, but my current cooler is not going to do much more. I'm a bit disappointed. I really thought I should be boosting around 4000 default and 4100 with PB2. Right now, it appears 4050 is my limit with PBO.
Which bios are you running?
 

stormlight

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Kamikazi,
You are EDC limited at the moment. Increase your Vcore (voltage) should help you reduce EDC (current) but you are close to maxing out your PPT (core power limit) anyway. But higher VCore will help you with high frequency boost! These processor is power limited by default. Go to bios and unlock your PPT, TDC, and EDC then you will see the true computing power of these ryzen. This is not overclocking frequency, this is remove the power limit in cpu. You are fine as long as there is adequate cooling. Is your core voltage on auto? Since this thread is about cpu cooler for 3950X, Noctua D15 is well equipment to support 3950X with unlocked power limit. If the consideration is with power limit remained locked, the 3900X stock cooling should works just fine even for the 3950X :-P!

If you don't want to unlock power, you can leave Vcore on Auto and have VCore offset at -.1V. You should easily gain more performance ~20%. This just proves that there is much more potential with the processor without power limit. (1.48V/1.38V)^2 = 1.15 so 15% is power saving to gain around ~15-20% in performance. Close enough for me to consider it be linear! :-P
 
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Jamie Marsala

Limp Gawd
Joined
Mar 9, 2016
Messages
172
I got some more testing done tonight. Strange behavior though. When I booted up my computer, it wouldn't post and I eventually had to clear CMOS and start over. I loaded the same profile that was on it yesterday and now single core on the cpu just doesn't work as well. Boost tester shows weaker results with no core exceeding 4600 MHz. Yesterday, the entire good chiplet could boost over 4600 with several close to 4700. CB20 single core dropped from 528 to 509. Multicore also scores under 9000 with cpu clocking under 3900 MHz.

View attachment 214357

See above that PB2 is broken. Running CB20 multi with temps at 61C, only getting 3838 MHz. This should boost higher, no? The only tweaks I've made in BIOS are memory settings. Everything else is stock. When I enable PB2 in Ryzen Master, I get the same results as default. The same power limits are in place. I can, however manually boost the power limits with PBO in BIOS and get some improvements. Then, in Ryzen Master, I can enable PB2, and it works. I can score just over 9300 in CB20 multi. Clock speed tends to hover around 4050 MHz. Temps hit the low 80s. I don't think I can get much more out of it. I haven't tried any all core overclocking, but my current cooler is not going to do much more. I'm a bit disappointed. I really thought I should be boosting around 4000 default and 4100 with PB2. Right now, it appears 4050 is my limit with PBO.
Your Power settings in BIOS are set to the CPU ones and not the Motherboard ones so they are all at the default now, which limits total power to the CPU. See your PPT, TDC, and EDC are not lower than Dan_D are. On my board they are PPT @ 500 TDC @ 144 and EDC @192. Which are what my board supports
 

thesmokingman

[H]ardness Supreme
Joined
Nov 22, 2008
Messages
5,699
20C is 68F, that's not cold. It is winter here and I have the heat set to 65F in the house but It's warmer in the room the pc is in, probably 70-72F, case temp of 30C is fairly accurate based on temp sensors on the mobo. It goes up in lock step with coolant temp. My rad does not pull directly from outside, so it's getting a mix of case and fresh air. Not ideal but as good as I could manage with my case and enough to keep things cool.
That's not how ambient works, you don't just choose a number and go with it. The whole point is to give others a way to correlate their cooling performance with yours. However your numbers don't add up. And 68f is damn cold, and for the purposes of comparing cooling will definitely make your cooling seem a helluvalot better than it actually is w/o knowing the ambient.
 

Dan_D

[H]ard as it Gets
Joined
Feb 9, 2002
Messages
55,503
Kamikazi,
You are EDC limited at the moment. Increase your Vcore (voltage) should help you reduce EDC (current) but you are close to maxing out your PPT (core power limit) anyway. But higher VCore will help you with high frequency boost! These processor is power limited by default. Go to bios and unlock your PPT, TDC, and EDC then you will see the true computing power of these ryzen. This is not overclocking frequency, this is remove the power limit in cpu. You are fine as long as there is adequate cooling. Is your core voltage on auto? Since this thread is about cpu cooler for 3950X, Noctua D15 is well equipment to support 3950X with unlocked power limit. If the consideration is with power limit remained locked, the 3900X stock cooling should works just fine even for the 3950X :-P!
I think I understand what's going on here and why so many people are confused on this topic. I think I just fully figured it out, so I'm right there with you guys despite having had half a dozen of these Ryzen 3000 series CPU's on my test bench. The default values in your BIOS are Precision Boost 2. These PPT, TDC and EDC values are going to be the same for every 3950X as these are the OEM values of the CPU itself. For reference, these are 142w (PPT), 95A (TDC) and 140A (EDC). When you enable auto-overclocking in Ryzen Master, it isn't PB2 that we are enabling. It sounds like that's what it is, but it isn't. If you look at it, the PPT value increases to 500w. The TDC value increases to 245A and the EDC value changes to 280A. When you enable PBO in Ryzen Master, it does exactly the same thing. You get identical PPT, TDC and EDC values as auto-overclocking.

There has been some talk in the Threadripper thread about a 68c rating number. I noticed that if you leave Ryzen Master's auto-overclocking and PBO alone, you will see a maximum temperature of 68c. At least, this has been true for all of my test configurations and some of the numbers reported by the air cooling guys seem to track with this. What I think is happening here is that the 68c isn't the maximum rated frequency, despite what AMD's website would have us believe. Nor, do I think this value is for Threadripper CPU's alone. I think this is the target temperature that AMD shoots for on these CPUs. If the CPU can clock higher and still be within the PPT, TDC and EDC of PP2 and remain 68c, it will. However, for the air cooling guys, they'll hit 68c sooner than someone on a good AIO or custom cooling will and therefore see lower clocks despite all of us hitting the PPT, TDC and EDC limits.

When you raise the PPT, TDC and EDC, your clocks will increase. However, so will your CPU temperatures. At that point, thermal throttling is 95c. So, to summarize. Yes, you can use air cooling with these CPU's. However, you will NOT see the same clocks as those of us on custom water or really good AIO's. Please stop trying to perpetuate some myth that a D15 is all you need or that the Wraith Prism cooler that comes with the 3900X would have worked too. Technically, the CPU would have run with it and a D15 will work OK, but you will be losing performance. You will be neutering your $750 CPU. You will be seeing less performance than those of us who are willing to forge ahead with liquid cooling of some kind.

This confused even me or I'd have reworded my previous and lengthy post on the subject. However, most of what's in there holds true. It's worth noting that the same CPU is capable of 4.3GHz all core when manually overclocked and the PPT, EDC and TDC values didn't change much vs. PBO / Auto-overclocking in Ryzen Master. I saw a 1% increase on PPT and TDC, but EDC actually dropped quite a bit. I suspect this is because I had the voltage set to 1.4v manual, and under PB2 or PBO, the CPU can pull more voltage than that if it thinks it needs to. It normally only does it for brief periods but it does happen.
 

kamikazi

Limp Gawd
Joined
Jan 19, 2006
Messages
477
I got lots of explaining to do. Thanks for everyone's input. I apologize for hijacking this thread. Hopefully everyone learns something new.

Actually, if your signature is correct on your cooling, you are getting roughly what I'd expect. That's also in line with what others are seeing. What surprises me is that PBO would do anything for you as it achieved worse results in my experience. Under full load I can hit 80-85c on my test CPU, except that I'm on custom water and my clocks are higher. I'm at 4.1GHz to 4.15GHz with PB2 enabled. PBO was worse coming in at 3.9-4.0GHz.
I just thought that I would get higher than mid 3800 MHz speeds at default settings running CB20. My 3900x would sit right around 4000MHz at stock. I know the 3950x is 4 more cores, but I thought I'd be in the mid 3900s due to better silicon. The temp is right around 60C, so I'm not thermally limited there. Setting auto overclock/PB2 in Ryzen Master just kept the same default limits on PPT, TDC, and EDC which are shown in the screenshot I posted above, so I got the same performance. What is strange is that after I set the PPT, TDC, and EDC limits higher in the PBO settings in BIOS, then open Ryzen Master and select Auto Overclock/PB2 and let it reboot, Ryzen Master then uses whatever I set the limits to in BIOS when set to auto overclock. It's like a PB2 and PBO hybrid, but it's essentially just PBO I guess. I assumed that when auto overclock took over, it would set limits back to the AMD settings, but it didn't, so I can then tweak them to any point lower than what I set in BIOS via Ryzen Master and let it roll, getting me a higher clocks, and more heat of course.

Which bios are you running?
1201 which was released on 12/3/19.

Kamikazi,
You are EDC limited at the moment. Increase your Vcore (voltage) should help you reduce EDC (current) but you are close to maxing out your PPT (core power limit) anyway. But higher VCore will help you with high frequency boost! These processor is power limited by default. Go to bios and unlock your PPT, TDC, and EDC then you will see the true computing power of these ryzen. This is not overclocking frequency, this is remove the power limit in cpu. You are fine as long as there is adequate cooling. Is your core voltage on auto? Since this thread is about cpu cooler for 3950X, Noctua D15 is well equipment to support 3950X with unlocked power limit. If the consideration is with power limit remained locked, the 3900X stock cooling should works just fine even for the 3950X :-P!

If you don't want to unlock power, you can leave Vcore on Auto and have VCore offset at -.1V. You should easily gain more performance ~20%. This just proves that there is much more potential with the processor without power limit. (1.48V/1.38V)^2 = 1.15 so 15% is power saving to gain around ~15-20% in performance. Close enough for me to consider it be linear! :-P
I unlocked PPT, TDC, and EDC and set them to 300, 150, 300 I think and then tweaked from there in Ryzen Master, but I didn't post that above. I was able to get up to 4050 MHz in CB20 with a max temp of 82C with lots of nice fan noise. Core voltage is on auto. When I had the 3900x installed, I did run a -0.1 offset for a while. I didn't get quite the boosts though. Are you saying I will get better performance by unlocking PPT, TDC, and EDC while running a voltage offset?

Your Power settings in BIOS are set to the CPU ones and not the Motherboard ones so they are all at the default now, which limits total power to the CPU. See your PPT, TDC, and EDC are not lower than Dan_D are. On my board they are PPT @ 500 TDC @ 144 and EDC @192. Which are what my board supports
I did mess with changing them all around and setting it so that TDC was the limiting factor to see what it would do. I will probably mess around tonight and try to tweak it so I max out around 85C in CB20.
 

Dan_D

[H]ard as it Gets
Joined
Feb 9, 2002
Messages
55,503
I got lots of explaining to do. Thanks for everyone's input. I apologize for hijacking this thread. Hopefully everyone learns something new.



I just thought that I would get higher than mid 3800 MHz speeds at default settings running CB20. My 3900x would sit right around 4000MHz at stock. I know the 3950x is 4 more cores, but I thought I'd be in the mid 3900s due to better silicon. The temp is right around 60C, so I'm not thermally limited there. Setting auto overclock/PB2 in Ryzen Master just kept the same default limits on PPT, TDC, and EDC which are shown in the screenshot I posted above, so I got the same performance. What is strange is that after I set the PPT, TDC, and EDC limits higher in the PBO settings in BIOS, then open Ryzen Master and select Auto Overclock/PB2 and let it reboot, Ryzen Master then uses whatever I set the limits to in BIOS when set to auto overclock. It's like a PB2 and PBO hybrid, but it's essentially just PBO I guess. I assumed that when auto overclock took over, it would set limits back to the AMD settings, but it didn't, so I can then tweak them to any point lower than what I set in BIOS via Ryzen Master and let it roll, getting me a higher clocks, and more heat of course.
4.0GHz is actually slow for the 3900X as well. The one I have here will hit 4.15GHz in Cinebench R20. Again, silicon quality isn't the limiting factor. TDP and having the same PPT, TDC and EDC as the 3900X is. And yes, as I explained, you are thermally limited, its just not apparent because your hitting PPT, TDC And EDC limits first. If you remove those limits, then you'll hit the thermal wall pretty quick. Even if you don't hit the thermal limit, you still have the shitlet and the worst of the CCX's that will hamper your efforts further. This is largely why you can have more thermal headroom and still not reach better boost clocks. This isn't like an Intel CPU where each and every core can hit the maximum rated boost clock. In fact, it's quite the opposite. At best you've got one or two cores that can do 4.7GHz. You've probably got one CCX that can do 4.4GHz and the rest will do a bit less.

I unlocked PPT, TDC, and EDC and set them to 300, 150, 300 I think and then tweaked from there in Ryzen Master, but I didn't post that above. I was able to get up to 4050 MHz in CB20 with a max temp of 82C with lots of nice fan noise. Core voltage is on auto. When I had the 3900x installed, I did run a -0.1 offset for a while. I didn't get quite the boosts though. Are you saying I will get better performance by unlocking PPT, TDC, and EDC while running a voltage offset?
I'm not sure what he's saying but the reality is that unlocking PPT, TDC and EDC will get you slightly higher clocks but you will see much higher thermals. BTW, 300, 150 and 300 aren't likely enough. Using auto-overclocking and PBO, I had higher limits by default. 300w is probably enough for PPT and your EDC is likely fine as well, but your TDC is extremely low.

I did mess with changing them all around and setting it so that TDC was the limiting factor to see what it would do. I will probably mess around tonight and try to tweak it so I max out around 85C in CB20.
At 4.12GHz I can hit 80c or more on custom water cooling. Although, that's for something like Blender. For Cinebench I'm at 76c. Using an H100i I don't know how close to your target you'll get.
 

kamikazi

Limp Gawd
Joined
Jan 19, 2006
Messages
477
4.0GHz is actually slow for the 3900X as well. The one I have here will hit 4.15GHz in Cinebench R20. Again, silicon quality isn't the limiting factor. TDP and having the same PPT, TDC and EDC as the 3900X is. And yes, as I explained, you are thermally limited, its just not apparent because your hitting PPT, TDC And EDC limits first. If you remove those limits, then you'll hit the thermal wall pretty quick. Even if you don't hit the thermal limit, you still have the shitlet and the worst of the CCX's that will hamper your efforts further. This is largely why you can have more thermal headroom and still not reach better boost clocks. This isn't like an Intel CPU where each and every core can hit the maximum rated boost clock. In fact, it's quite the opposite. At best you've got one or two cores that can do 4.7GHz. You've probably got one CCX that can do 4.4GHz and the rest will do a bit less.



I'm not sure what he's saying but the reality is that unlocking PPT, TDC and EDC will get you slightly higher clocks but you will see much higher thermals. BTW, 300, 150 and 300 aren't likely enough. Using auto-overclocking and PBO, I had higher limits by default. 300w is probably enough for PPT and your EDC is likely fine as well, but your TDC is extremely low.



At 4.12GHz I can hit 80c or more on custom water cooling. Although, that's for something like Blender. For Cinebench I'm at 76c. Using an H100i I don't know how close to your target you'll get.
Thanks again for your analysis. I guess I was thinking that my chip could pull higher clocks at lower power draw due to some higher quality silicon, but, I agree with you, I'm thermally limited and can't see it until I unlock it all and release the hounds. I'll find out tonight and post back.
 

stormlight

n00b
Joined
Jan 6, 2020
Messages
19
I unlocked PPT, TDC, and EDC and set them to 300, 150, 300 I think and then tweaked from there in Ryzen Master, but I didn't post that above. I was able to get up to 4050 MHz in CB20 with a max temp of 82C with lots of nice fan noise. Core voltage is on auto. When I had the 3900x installed, I did run a -0.1 offset for a while. I didn't get quite the boosts though. Are you saying I will get better performance by unlocking PPT, TDC, and EDC while running a voltage offset?
This is ~15-20% in performance not clock. As I had said earlier in post, most program cannot take the full advantage of all the thread. CPU utilization was not at 100%. I have to run two instances of handbrake to witness this! Hey, what is your package power, cooler and fan rpm? Yes, I get 4050MHz as long term base frequency too.

When you raise the PPT, TDC and EDC, your clocks will increase. However, so will your CPU temperatures. At that point, thermal throttling is 95c. So, to summarize. Yes, you can use air cooling with these CPU's. However, you will NOT see the same clocks as those of us on custom water or really good AIO's. Please stop trying to perpetuate some myth that a D15 is all you need or that the Wraith Prism cooler that comes with the 3900X would have worked too. Technically, the CPU would have run with it and a D15 will work OK, but you will be losing performance. You will be neutering your $750 CPU. You will be seeing less performance than those of us who are willing to forge ahead with liquid cooling of some kind.
I am not sure where you have read the Noctua D15 hit 95C with 3950x or 3900x with stock frequency. I have a 3900x with Noctua D15 and I am getting 76C with 100% cpu utilization with ~165W package power. It is a fact: not myth! 80C@~200W package power. I am only only using 1 of the 2 fan setup. I had made it very clear in the past post. All this is for stock and undervoltage without overclocking/PBO. Wraith Prism works because it is measured against package power with default locked power limit. (~165W)

This confused even me or I'd have reworded my previous and lengthy post on the subject. However, most of what's in there holds true. It's worth noting that the same CPU is capable of 4.3GHz all core when manually overclocked and the PPT, EDC and TDC values didn't change much vs. PBO / Auto-overclocking in Ryzen Master. I saw a 1% increase on PPT and TDC, but EDC actually dropped quite a bit. I suspect this is because I had the voltage set to 1.4v manual, and under PB2 or PBO, the CPU can pull more voltage than that if it thinks it needs to. It normally only does it for brief periods but it does happen.
Was this test done while cpu was at 100% utilization? When my PBO is on auto so I see that all core can go 4250 before but drop out like 5 sec later to 4100/4050.

All,
I am not sure you guys understand what I had been implying but I will make it explicit. Please post your package power along with your temperature. Under utilized cpu with high frequency will run cooler than fully utilized cpu at slower frequency. Prime95/OCCT does not fully max out cpu utilization. Cinebench R20 can peak fully at one point but does not constantly. PBO is consider to be overclocking up to +200MHz on top of PB2. PB2 is turbo boosting: it is not overclocking and is within AMD specification.
 
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