Haswell and Prime95

mikey_rules

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My CPU doesn't like Prime95, not even for 5 seconds. I get a crash so hard that it won't even BSOD. When Windows boots and realizes what just happened, it tells me it was a BSOD 124 error every time. I can stress test with AIDA64 Extreme, Cinebench, and Intel Burn-In, all for 24+ hours. My concern is not being able to use Prime95 for stressing, but for using the program for doing nerdy things like finding prime numbers via the Mercenne method and having astronomically large exponents.

Any suggestions as to whether or not I'll ever run Prime95 on my setup? And if so how?

Thanks in advance.
 

PcZac

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Prime95 pulls more wattage than any real world application, it's good at telling you quickly if an overclock might fail over 24 hours with a less intense stress test, but it's probably not good for your CPU in the long run. If you are stable in other stress tests, and never get BSOD, I wouldn't worry about it.
 

mikey_rules

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It would crash at stock speeds, but after about the 30 hour mark. And that's with everything at "optimization settings" in BIOS.
 

Araxie

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keep using P95 and you will fry your chip, its well known that Prime95 shouldn't be used with any haswell chip since the version 27.9. IF you want to use P95 you have to use 27.9 and earlier.. its recommended by almost every manufacturer out there.. because yes, it make those chips to fail even at stock speed so isn't reliable and put just abysmal stress without reason, without take into consideration insane voltages. the most recommended application its Aida64.. p95 its today just a cooler tester and nothing more, something like furmark.. useless.. nothing better than real world apps to test a overclock.
 

durquavian

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I prefer IBT (Intel Burn Test). Of course I am on an AMD system, but P95 gives issues on AM FX CPUs. Many others like Aida64 as well, although I only used once so cant really comment.

If all you do is game and leisure activity, P95 stability is not paramount. If it is for work, how you make money, then it is a bit more important.
 

GeneO

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If you want to use prime95 to test stability on the latest 28,5, use a custom FFT size of 1344 - 1344. This will tests the AVX FMA3 -instructions for stability without unduly overheating the chip. Keep an eye on your core voltage as this can shoot up on some chips.
 

mikey_rules

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keep using P95 and you will fry your chip, its well known that Prime95 shouldn't be used with any haswell chip since the version 27.9. IF you want to use P95 you have to use 27.9 and earlier.. its recommended by almost every manufacturer out there.. because yes, it make those chips to fail even at stock speed so isn't reliable and put just abysmal stress without reason, without take into consideration insane voltages. the most recommended application its Aida64.. p95 its today just a cooler tester and nothing more, something like furmark.. useless.. nothing better than real world apps to test a overclock.

Thank you for clarifying, I haven't been able to find a straight answer as to why Haswell and Prime95 don't get along. I mostly use my CPU for video compression (hello, x265) and very light gaming (Starcraft 2). Only video compression pushes the CPU, but I've never had it crash while running.
 

Araxie

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Thank you for clarifying, I haven't been able to find a straight answer as to why Haswell and Prime95 don't get along. I mostly use my CPU for video compression (hello, x265) and very light gaming (Starcraft 2). Only video compression pushes the CPU, but I've never had it crash while running.

basically because it's old and because it does not implement AVX2 very well as isn't part of the original code (of course being so old, nothing strange), no matter how much update to the code the app receive its really showing the age and actually are newer and better applications to test a system stability as the mentioned Aida64 which was re-structured to be in a optimum compatibility with haswell specially with first haswell gen (4670K or 4770K for example) which have an awful implementation of the integrated voltage regulator on die and those tend to deliver insane amount of voltage even at stock speed while using prime95, in fact with Haswell-E there's a guide made by Asus which encourage people to not use Prime95 because it can kill the processor or even the motherboard because it put abnormal stress in the power circuitry to the motherboard (specially overclocked). so yes, that's the main thing.. nothing its better than real world usage..
 

sblantipodi

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Prime95 pulls more wattage than any real world application, it's good at telling you quickly if an overclock might fail over 24 hours with a less intense stress test, but it's probably not good for your CPU in the long run.

completely agree with this post.
prime95 is the best software you can use to quickly test for stability.

10 minutes of prime will not hurt your CPU and will tell you if it is stable better than 24hours of other tests.
 

w00t69

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always wondered. Because the second you hit small fft's and hit start even with my swiftech 220x the cpu hits 79c.

With aida64 the average temp is 69c across all cores.
 
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what stress tests do people recommend to check if a haswell-e overclock is stable then? i'd been using AIDA64 so far. what of Intel's Extreme Tuning Utility? Cinebench? OCCT?
 

wabbitseason

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keep using P95 and you will fry your chip, its well known that Prime95 shouldn't be used with any haswell chip since the version 27.9. IF you want to use P95 you have to use 27.9 and earlier.. its recommended by almost every manufacturer out there.. because yes, it make those chips to fail even at stock speed so isn't reliable and put just abysmal stress without reason, without take into consideration insane voltages. the most recommended application its Aida64.. p95 its today just a cooler tester and nothing more, something like furmark.. useless.. nothing better than real world apps to test a overclock.

FYI, OP:

wabbitseason said:
"You shouldn't use the most taxing form of prime available, because Intel doesn't recommend it."



What he should have said is that haswell chips are so difficult to cool and incredibly poorly-designed for overclocking that overclockers have had to redefine the term "24-hour prime stable", because even with high-end cooling the chips can literally fail and damage themselves on the hottest and newest Prime settings. Even on your great watercooling setup your temps are higher than I'd prefer for year-round usage. This is unacceptable, obviously, and Intel deserves criticism for it.

Instead, apologists like Araxie have started to recommend you use older and less intensive versions of Prime95, in order to move the goalposts and redefine "stable under load" to something haswell can handle.
 

Araxie

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I didn't created any recommendation, all recommendations are made by intel, Asus, MSI and the rest of motherboard manufacturers, but I guess you are smarter than intel and Motherboard manufacturers when the things are related to power circuitry and VRMs... you say all that crap but also you don't read where i said " which have an awful implementation of the integrated voltage regulator on die and those tend to deliver insane amount of voltage even at stock speed while using prime95" im not a intel defender or AMD defender, but im not a Intel hater or AMD hater.. If they don't recommend to use prime95 with Haswell and Haswell-E because isn't designed to run correctly haswell chips as it can run Aida64? because aida64 Only FPU test can put the same heat or even more after 2 hours than prime95 small FFT, who I am to say anything contrary to that?. I am doing anything wrong transmitting to people what motherboard manufacturers say?. yes I critic how horrible its the design of have the voltage regulator modules on die, but can i change that? NO, Just recommend people to not use and done.. at the end of the things prime95 isn't even the successful ultimate stability test as it was years ago you can pass days of p95 and crash at the first 5 minutes of real world usage. so, if you aren't adding anything useful to the thread, why just bother with discredit me?.. if you are happy with that, gratz be happy. im just helping people here.. if you want to add something to help the OP, excellent..
 

Hurin

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All I can say is that Prime95 exposed an instability in my overclock that Intel Burn Test, AIDA, and Intel's overclocking tool all failed to expose.

So long as you set the minimum FFT size to 512, you shouldn't see crazy temperatures (my 4770K @ 4.4GHz stays below 80c).

I tried all the other stability tests and came up clean. But would get the odd system hang or other strange behavior. So I went back to Prime95. Only after I could pass a 24-hour Prime95 run with appropriately tuned down OC did the stability issues disappear.

Don't count Prime95 out. It still has its uses.
 

Arct1c0n

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I was trying Prime 95 on my new 4790k this weekend and the tempratures shot up to 90c suddently, and I completely freaked out and emergency shut down my new computer. Apparently haswells don't like ancient prime95 so i'm not gonna bother with it, I use AIDA64 now
 

Hurin

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I was trying Prime 95 on my new 4790k this weekend and the tempratures shot up to 90c suddently, and I completely freaked out and emergency shut down my new computer. Apparently haswells don't like ancient prime95 so i'm not gonna bother with it, I use AIDA64 now
Try a custom FFT minimum setting of 512k. Also, turn off adaptive voltage while figuring out your max overclock. AIDA64 didn't expose my OC's instability while Prime95 set as described did.
 
D

Deleted member 82943

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hmm, reading this thread, perhaps I sold my haswell chip prematurely. I was running FFTs of 8k and getting ~90C or so

makes me wonder what skylake will do
 

Hurin

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hmm, reading this thread, perhaps I sold my haswell chip prematurely. I was running FFTs of 8k and getting ~90C or so

makes me wonder what skylake will do
Any Haswell will quickly reach 100c and throttle with adaptive voltage enabled and Prime95 running untweaked.
 

Dan_D

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You can't generally use adaptive voltage with Haswell CPUs and Prime95. That and some other applications cause the CPU to call for more voltage from the IVR than the CPU actually needs creating stability problems. Usually the stability issues stem from of overheating. If you want to use Prime95 you need to use manual voltage and set it to the minimum level you need for stability at a given clock speed.
 

Zepher

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I was testing with prime95, but I happen to have version 25.8, didn't know the newer version wreaked havok on the haswell chips.

i7-4790k-H80i.jpg
 

Arct1c0n

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Try a custom FFT minimum setting of 512k. Also, turn off adaptive voltage while figuring out your max overclock. AIDA64 didn't expose my OC's instability while Prime95 set as described did.

That was on stock clock and voltage and I would much rather keep adaptive voltage on rather then burning put my CPU for epeen reasons , but you go ahead and knock yourself put
 

mikey_rules

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You can't generally use adaptive voltage with Haswell CPUs and Prime95. That and some other applications cause the CPU to call for more voltage from the IVR than the CPU actually needs creating stability problems. Usually the stability issues stem from of overheating. If you want to use Prime95 you need to use manual voltage and set it to the minimum level you need for stability at a given clock speed.

Well said, especially after what has been posted here and in other threads I've been reading elsewhere. Makes sense too: Prime demands more performance, adaptive voltage gives it, and we have instability problems. Too bad Haswell heats up so much, delidding or not.
 

mikey_rules

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@Zepher What kind of a cooler do you have on that puppy? 50°C max temp? Must surely be the stock cooler ;)
 

Zepher

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@Zepher What kind of a cooler do you have on that puppy? 50°C max temp? Must surely be the stock cooler ;)

Corsair H80i with the stock fans in my HAF-XB case.
Corsair-H80i.jpg



here is an idle temp
coretemp-4790k-really-cold.jpg
 
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D

Deleted member 82943

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Any Haswell will quickly reach 100c and throttle with adaptive voltage enabled and Prime95 running untweaked.

Well fuck me. Oh well it is likely be used now instead of sitting doing 20 second runs of p95
 

Zepher

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Are those delidded idle temps?

Try running the newest p95 with 512k FFTs

no, stock untouched chip with whatever Thermal paste was on the Corsair.

why does my clock speed drop to 4Ghz with the 28.5 version?
prime95-512k.jpg



Cool, another HAF XB owner!

Ya, I have 2 of these case now, I really like the look of them. don't really care for working on them though since it is really tight under the motherboard tray if you have to add a cable or a drive to the system.
I recently added a 3.5" hot swap tray and had to add a power cable to the PSU and try and plug it in and then fish it to the cage.
 
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Dan_D

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My first response was to say it was probably heat related but Core temp shows really good temperatures in your screenshot. I've seen that sort of thing before on GIGABYTE motherboards with ES chips but not with retail CPUs running in reasonable temperature ranges.
 

Zepher

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My first response was to say it was probably heat related but Core temp shows really good temperatures in your screenshot. I've seen that sort of thing before on GIGABYTE motherboards with ES chips but not with retail CPUs running in reasonable temperature ranges.

I tried it twice, starting it up when the clock was at 4.4Ghz (it cycles from 4.2 - 4.4 when it is just idling), and both times it dropped to 4Ghz when Prime started.
Coretemp-voltage.jpg
 

Hurin

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That was on stock clock and voltage and I would much rather keep adaptive voltage on rather then burning put my CPU for epeen reasons , but you go ahead and knock yourself put
First, no need for the snark or hostility.

Second, I too prefer adaptive voltage on. Which is why I do have it turned on. Because I'm no longer validating my overclock or running Prime95. Though, now that I have done so and I have specified my adaptive voltage range, I can run Prime95 with min FFT of 512 and not see anything about 75c or so.

Adaptive voltage should be turned off while a careful Overclocking validation process is underway.

CPU Core Voltage: Adaptive Mode
Offseet Mode Sign: +
CPU Core Voltage Offset: .001
Additional Turbo Mode CPU Core Voltage: 1.290

That latter is only applied when the CPU enters turbo mode.
 

AdamK47

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I tried it twice, starting it up when the clock was at 4.4Ghz (it cycles from 4.2 - 4.4 when it is just idling), and both times it dropped to 4Ghz when Prime started.
Coretemp-voltage.jpg

Don't you turn the heat on in your house? 45F to 50F would be way to cold for me.
 

Zepher

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Don't you turn the heat on in your house? 45F to 50F would be way to cold for me.

The house has the heat turned up but I am in the garage.
My friend loaned me a kerosene heater to warm up the garage a bit.
cubicle-cold.jpg
garage-warm.jpg
 
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