Hi all.
I have been playing around with overclocking my cards, 2x5850 1x5870, but I'm not sure I'm doing it right.
My 5850's are clocked at 885/300 and spit out around 366mh/s, I think that's not too bad. The 5870 on the other hand, I have a feeling Im not pushing enough. It's currently clocked at 910/300 and spitting out ~412mh/s. When reading up on other people's results, I noticed that different memory speeds are used, generally between 300-350, how does the core clock correlate to the memory clocks?
How much should I push a card? It may seem as a stupid question, but other than BSOD's, freezing up, rebooting the pc, is there things that can indicate unstable OC? Noticed at higher clocks my miner restarts more often, but to be honest I cannot rule out that it's simply something with the internet-connection between me and btcguild (Im in Europe). Higher overclocks also gives me higher stale counts, can raising the memory speed decrease those? The system itself does not hang or anything, so that is why I'm not sure if the cards are pushed enough. Should I just overclock till the system restarts, shows visible graphic errors, etc, and then set the core clock down like 5-10mhz?
I am using Windows 7 32bit, AOCLBF 1.75, Phoenix 1.5 with the 07-17-11 kernel, AMD 11.7 with included SDK.
Motherboard Asus P5K, C2D e6850 (or e6750, can't recall atm) 2x1gb RAM, Wireless network card (could that mess with my stale share count/miner restarts?)
Two Sapphire Xtreme 5850's and one XFX 5870 HD-587X-ZNFV.
Any help would be greatly appreciated.
I want to start out by saying I won't have my first 5850 until Wednesday so I can't really help with specific clock numbers. I know the 5830's best memory clock is 350 any more then that does nothing any less the megahash starts to drop. You just need to look up what people are saying for memory for the 5850 and test going up and down seeing where the sweet spot for your card is. The reason you drop the memory is because you get nothing extra from from the memory being so high. By lowering the memory you'll make the card run cooler, it will consume less electricity and as a side effect of the lowered heat allows you to push the core clock higher.
Each 5850 and brand of 5850 is different my suggestion is find what seems to be the average overclock speed(that is higher then what you have now) and try it. If the drivers crash or the heat is too high lower the core clock a little until its at a safe temp.
Did I miss anything you wanted answered?