I have a radeon 6950, I tried overclocking it in the past, even found a safe overclock that didn't garner me any artifacts and crashes, but I put it back to default, didn't want to run the risk of causing it to uhm... spontaneously combust. ^_^ I've overclocked my CPU and it's been golden for quite awhile. So I do have general OC experience but I want to get a few pointers on what the risks are of GPU overclocking.
So my radeon 6950 even when overclocked at a voltage of 1.180 doesn't poke over 75C during gaming, so that's pretty good. I managed to get it to 890/1325 stable. (as opposed to 800/1250) If I go to 900/1325 or 900/1350 my computer locks up and then I gotta restart. Not a golden card, that's for sure, but if I can get more out of it, why not?
So I would like to know the following.
1 - What are the general risks of GPU overclocking? Even if I keep the temperatures under control and keep everything, do I still annihilate part of my GPU's life time? Would a radeon 6950 last me a couple years while overclocked?
2 - How should I go about testing the card for overall stability?
If you don't go too crazy on the overclocks the magic smoke won't escape and you won't brick your video card. I have overclocked all my video cards for the last 10 yrs with no ill effects. I also use aftermarket coolers to make sure they don't overheat. Heat is the big issue and too much voltage causes heat.
I've pretty much hit the max allowed voltage on this card. I can see why since its a reference design. I see no control for the memory voltage so I best only nudge the memory a bit.
Saying this because i dropped the memory to 1300MHz and bumped the core to 930 MHz to no ill effects. At least to no ill effects during a single run of 3dmark 11. Gonna try 950 on the core. If that works i'll leave it at that, if not ill bump down to 930 again and continue testing.
Already got artifacts at 950, my display driver crashed at 940 with, stragenely enough, no artifacts. So I'm going ro run 3dmark 11 for about 5-10 loops at 930. If that works i'll start the true test. Actual games. I'm not worried about temperature as I've never seen this card go over 80C anyway. But i'll still keep an eye on the temps to be safe.
My chip isn't all that great apparently, but im gonna run unigine heaven for about 20 minutes to confirm whether my current clocks are feasible. c: It's all fun for me, so long as my temperatures are acceptable. (Which they are.)
There's never much risk in overclocking until you start messing with voltages. When you start increasing voltages, if your card doesn't have the power circuitry to handle it, you can shorten the lifespan of your card. Go nuts with voltage tweaking and you can dramatically lower the card's lifespan, though that's unlikely to happen unintentionally.
I'm certainly not going crazy over the voltages. (At least I think so) I have sapphire's reference card but it's a good one. The temperatures never go over the top, and sapphire did put a 1.180 cap on the voltages. (If I was to buy a toxic I would have been able to do more. 1.180 doesn't create much heat so, I feel safe.)
Safe to say that im stable at 910/1275. (Though only true gaming will tell that, but by running unigine for 15-20 minutes and repeated 3dmark 11 tests, I think im solid) Lets see the difference in performance on this card in 3dmark 11. (Which is surprising.)
910/1275 gives me a score of P5899 (I'm just gonna say P5900 )
800/1250 (Stock Clocks) gives me a score of P5368. (Im surprised, as people were in the upper P4000 range.)
Not a major increase, but im proud of what i've done here. I'm gonna keep it as well. ^^ Any other tips?
I recommend Kombustor to test overclocks if you are running it only for 20 minutes. Thats far too little time, but I feel Kombustor is the most solid way to get a general feel if its stable. I run it for 30 minutes, and it typically heats the card another 20 degrees celcius further than gaming normally would.
I've found that 100% of the time that an overclock has run kombustor for more than 45 minutes, its stable and won't crash.