7950 coming today, help with OC?

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Fahrenheit

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Got a Sapphire Radeon HD 7950 coming. Bought this mainly for the value you get when you OC the card. I've never OCed anything before. Plan to use the TriXX too to OC and FurMark for stability. Can anyone just kinda walk me trough the basics?
 
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Well, I wouldn't use Furmark for stability, you should use heavy games like crysis series and play for at least 1 hour.

Always start changing only the GPU clock without change voltage, until you find a stable clock... after that start rising the voltage and the clocks and after that you start to changing memory clocks..

Always keep an eye on Temperatures, for 7950 keep the GPU temp under 86C to be safer.
 
For quick and easy OC without worry, you can just go with base clock +100, mem clock + 40, and the power slider to +20%. I do manual fan at 50%, but that part is up to you. This is n CCC, with stock voltage.

In trixx, I would focus on the fan profile. START it at 40% at min temp, awork up from there. Example:

35c - 40%
45c - 42%
55c - 44%
60c - 48%
65c - 52%
75c - 55%
80c - 60%
85c - 80%
88c - 95%

This gets you fan movement ahead of the card's actual normal 3d temps, preventing the heat from spiraling ahead too much to prevent spikes. If you hit 80c, you need to be running pretty audible fan levels. Once you hit 85c, we need to reign it in fast.

Just a rough estimate.

Most people strongly recommend not upping voltage over ~1.2, core clock over ~1100, and mem over 1400. Those limits all require pretty exceptional cards in the given area, and if you are OC ing to ~1000-1050, then stock to 1.15 would be my guess. The higher voltage tends to give stability at higher core clock, but quickly presents heat and wear issues.
 
Link is broked at work here. The BIOS switch is on the Vapor-X, and maybe the FLEX. If you move it, my understanding is that it will move the voltage up, as well as core clocks. I have seen people post saying that it also locks the voltage when done. Mine is set that way, and it is not an issue for me to get 1050/1400 perfectly stable.

Note: VRAM is ECC. This means that if you overclock it just a little too much, you don't get artifacting, but you will LOSE a bit of performance due to error correction and compensation taking a few cycles.

Keep that in mind, as even the big 1600+ mem OCs don't give much return. I steal what I can and get out of the shop, when it comes to GPU RAM.
 
Fahrenheit said:
Thanks, Ill spend most of my time on the GPU core then.
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While the post above you might push you away from OC'ing the ram, the fact of the matter is that you will get more performance out of overclocking your mem than your GPU clock for clock.

Honestly its very simple to do - just keep increasing the OC on the mem slowly until you see that its unstables (crashes) or you see the benchmark result lower than the previous run with less OC. This will tell you the error-correcting has kicked in and you can back off - simple.
 
Any benchmark based upon GPU will work. You are just looking for the point where you stop gaining performance. Just to be sure, once you see lack of gain, re-run then bench at least once to verify it isn't just a bad sample.
 
Good luck with your 7950. They're good cards.

When ram speed is the same a 7950 will often catch a 7970 if it's running 25MHz faster on the core. So it would need 1125MHz on the core to catch a 7970 in some situations @ 1100.

My 7950 will do up to 1150|1630 1193 voltage. I run it @ 1090|1630 1150 voltage 24/7. It gets too loud for my tastes @ 1150MHz. Of course, I always set power control to +20% when I OC.

I OC with Trixx 4.4.0b-MOD

http://www.overclock.net/t/1265543/the-amd-how-to-thread#post_17399313

Enjoy your card :)
 
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UPS man came with my card just as I finished up cleaning. Great how that works out sometimes. Got the new card in and installing a fresh copy of windows 7 now. Can't wait!


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I know this will sound odd, but the absolute BEST game I have found for overclocking stability is Mass Effect.
Very first planet your on there is a this rock structure around this area are particles floating in the air. If you OC is not stable every once is a while you will see a white dot flash where the particles are floating.
You have to run around and look for the flash, but that game is insanely picky about overclocks.
 
Man no matter how many times I do it the install speed of windows on an SSD impresses me. Takes longer for windows update to catch up them install the OS.
 
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Alright, first question. In TriXX it shows my VDDC as 1250. Does that mean out of the box its at 1.25 volts? Thats already higher then what people say the max should be.
 
If you got an overclocked/boost version they come with higher voltage, the good news is.. you probably is going to reach 1100mhz on the core or more :)
 
Fahrenheit said:
Alright, first question. In TriXX it shows my VDDC as 1250. Does that mean out of the box its at 1.25 volts? Thats already higher then what people say the max should be.
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Yes this card comes with 1.25V out of the box, and like the poster above said, it means you can get to 1100 on the core without having to touch the voltage.
For reference, I can get to 1137/1585 on stock voltage and 1175/1685 @1.3V and these clocks are rock solid.
 
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Just messing around using Kombuster and Unigine to check stablity. About to pop into a game to see how stable this really is. Another question, see on the GPU clock graph how it goes up and down? Is that normal?
 
Yep, the card may vary its clock. It's not abnormal.

If you want a decent test try looping Unigine's Valley bench for one hour with the extreme HD preset.
 
Its normal, but its not a good thing. Have you set the power limit to +20%?

Either way, see if its game stable first, then worry about the core and memory throttling, if any.
 
Ok after running a ton of benchmarks and about 3 hours worth of Sleeping Dogs I think I can say I got my max OC. Ended up with GPU 1175 Mem 1675 VDDC 1.3. Even with Sleeping Dogs going for a while temp never got past 70.


Now, whats up with the throttling? I dont notice any choppiness in my FPS while playing, anything I can check to make sure nothing is wrong?
 
Just watch the GPU-Z bar. Play a game for awhile, then check back. If it ever even budges from 1175, something is probably wrong.

Do not worry if Furmark, OCCT, Kombuster, etc. cause it to drop.
 
Just played Crysis 2 for 45 minutes with GPUz running. Never budged off my set clocks. I think its a full screen windowed thing. Did have to back the core clock back to 1150 though.

I think I can push the memory harder but like the one guy said to far and it will start slowing me down so not sure if I should
 
I've found 79xx cards get finicky if you push them at 1.3V on air. You might get better stability at 1150MHz with 1.25V (hypothetically, test to be sure). Overall looks good so far, great clocks and temps. Also, don't use Furmark/OCCT or any of that other crap, just test in games.
 
Mr. K6 said:
I've found 79xx cards get finicky if you push them at 1.3V on air. You might get better stability at 1150MHz with 1.25V (hypothetically, test to be sure). Overall looks good so far, great clocks and temps. Also, don't use Furmark/OCCT or any of that other crap, just test in games.
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I'll give that a try now, so far 100% stability 1150 @ 1.3 but if I could drop it down to 1.25 and still be stable all the better for heat. Still may push the memory a little more though...
 
Seems like you definitely have a solid card.

I like running 1090|1630 because I can do that with my fan locked @ 33%. 1150|1630 requires around 60% to be managed well for me. The difference between those two clocks in the Valley bench is 3FPS. So it's measurable and not a big deal to me. I'd rather have my card more silent.
 
Jealous of all your temps, I have a Powercolor AX7950 Boost and at 1100/1400 my temps are at 77C 100% fan at 1440p on Heaven 4.0 max settings for about 45 min. Can't complain too much though I got it for $249.99. Powercolor set the BIOS to only increase the fan speeds when it reaches 81C or higher when set to auto, I am assuming that means its safe to keep it at 80 or less.
 
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Hmmm did just come back to my computer after sleeping all day and it would not wake up from sleep (I have sleep turned off in power settings, just power down monitor after 15mins). Don't think it could be a glitch related OC could it?


striker444 said:
Jealous of all your temps, I have a Powercolor AX7950 Boost and at 1100/1400 my temps are at 77C 100% fan at 1440p on Heaven 4.0 max settings for about 45 min. Can't complain too much though I got it for $249.99. Powercolor set the BIOS to only increase the fan speeds when it reaches 81C or higher when set to auto, I am assuming that means its safe to keep it at 80 or less.
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According to GPUz log I didn't go over 60 degrees while playing Crysis 3. Highest fan speed gets is 47% which is still not audible.



Another fast question. the overclocking built into CCC, if I slide the power thing all the way to +20 is that 1.3? Just thinking if I could get the same settings in CCC I could dump Trixx. One less program to worry about
 
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NO, the CCC settings do not affect the voltage, from what I know.

The +20 in CCC, is the same as the Board Power Limit slider in Trixx.
 
Thinking i'm getting close to locking down my final settings. One more question, compared to upping the core clocks how much heat does pushing the memory generate? Will pushing the memory faster make core temps go up?
 
Fahrenheit said:
Thinking i'm getting close to locking down my final settings. One more question, compared to upping the core clocks how much heat does pushing the memory generate? Will pushing the memory faster make core temps go up?
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If they're using the same heatsink, yes. However vRAM doesn't generate as much heat as the core, probably 30-50W depending on settings compared to 150-200W from the core.
 
I got mine (Dual-X Boost) up to 1120 / 1515 @ stock 1.25 V, but it becomes unstable after about 10 minutes. Now I notice that "force constant voltage" was disabled in Trixx, so I checked it and will test again. Could this improve stability?
 
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