Overclocking 5770

Hiya, first post for me.

I wanted to overclock my sapphire 5770 card to get slightly more performance from it. I've read in one or two articles overclockers getting overclocks (at stock voltage) of 890MHz for the GPU and 1430MHz for the memory easily up from the stock speeds of 850MHz/1200MHz. My question is why can I not get anywhere near these overclocks? Setting my GPU frequency at 890MHz I can only get up to 1300Mhz before the card fails in benchmarks. Cooling doesn't seem to be a problem with the card topping out at 61c on load. Thanks for your help

Have you fully tested the core overclock yet? It sounds (Not being disrespectiful, just the way that you have worded the post) like you have just stuck the core at 890 because you've read that somewhere that its possible...

Playing games, does the card crash? If the memory overclock is the problem, then you are more than likely to see corruption on screen due to the heat, but core overclocks tend to just freeze the game/card.

What are you using to test? Furmark? Games benches?

As for asking "Why can I not get anywhere near these overclocks", well, its never a guaranteed overclock, no matter how many people have achieved it. As the saying goes, your mileage may vary.

Let us know what you have attempted to do to get to your OC values and we can see what other advice we can give.

JP

PS. Catalyst version?
PPS. Welcome to the forums mate. Enjoy your stay! :)

Hiya, thanks for your reply.

I'm a relative newcomer to overclocking, but i'm a quick learner. I get no problems maxing out the core clock at 960MHz (using ATI's overdrive), but the maximum memory clock rate I can get is 1350MHz. I've tested out the overclocks using Furmark and the Crysis benchmark utility. When the overclock isn't stable I get a grey screen and need to restart the computer.

The reason I set the core clock at 890MHz is because I've read people have achieved better results keeping the core clock low and increasing the memory clock. But it seems my memory isn't stable at high clock rates, and even at 1350MHz I get LOWER performance than setting it at 1340MHz say, because of the cards ECC capability slowing down the performance.

I'm happy with what I've got, just a bit disappointed i'm not hitting the same levels as other overclockers have 'easily' managed. Also I'm using the latest version of catalyst.

Thanks again for any help or advice

Yeah, its annoying (I have the same thing with my Q6600, doesnt really go that far unfortunately :() whem you hear other people achieving it, though it may be a particluarly good batch, or you just got a slightly worse card.

Not really sure what to add tbh, as you are using the right tools to and test and determine stability. Does the memory still start declining in performance at the same point if you put the core back at stock - just to take that out the equation.

I gotta admit that I would rather see memory artifacts if the freq is too high, I've been trying to OC my 5850 and would make it a lot easier to just see corruption rather than benching again, and again, and again... :(

Yea the memory declines around that frequency no matter the core clock frequency. I agree, it would be much easier to see artifacts than relying on benchmarks to judge performance. I would rather the card show me something's wrong rather than it correcting it at the expense of performance. One last question, would increasing the supplied voltage help in overclocking the memory in any way? Thanks

About the voltage increase, I believe that it would, though I'm in no way condoning it really. I had a quick google and this page seems to state that the extra voltage will help to stabilise the frequencies. However, the special voltage tweak editions may ship with uprated components to withstand this behaviour, so seeing yours is stock just bear it in mind - esp if you melt the thing...

Personally, I stay away from voltages on GPU (for now anyway) even though I have just obtained access to the voltage on my 5850. Just dont think its worth the risk (which is odd seeing as I am pummelling my Q6600 with greater volts... But just have a think if the card is actually performing ok already, or if you just want to play the numbers game because others seem to be able to... If its ok, then I would get on with playing games mate!

Thanks for the info, interesting read. I'm pretty hesitant about increasing the voltage too, mainly because I don't want to lose the warranty if something ever happens! Guess I'll have to accept the overclocks I've managed, not that they're not bad! Anyway thanks for your help, I'd give you rep if I could :)