Well yeah, I mean if your card is only getting 45-60 on High, wouldn't you think your already pushing it? OC it a bit more maybe to like 900 core clock and up your fan speed, you'll probably be able to run Ultra above 30 fps. Like 50ish?
Get MSI Afterburner. Allows you to fan tweak and adjust the clocks. Remember though, don't push the bars all the way up just instantly. That's not how OCing works. Incrementally work your clocks up. Then test stability. Push your bars up to 900/1200 and see how it fares in MSI Kombustor. (If you have little squares [Artifacts] then your not stable) I recommend at least 60-70% fan speed when testing out. You may need to up voltage.
It's because you have to go into the afterburner text in the program files file then change the ATIUnofficialoverclocking to 1 then you can up it... If you look at all the reviews for the 6850, you see that all of them who reviewed OC (like Techpowerup) said they used MSI Afterburner and got it to 1000 core clock. So... Yeah..
You had 850/1200 running with no voltage added.
I would not jump right up to 900/1250, but you did.
Imo those artifacts came from the memory adjustment. The voltage does NOT effect memory voltage. Only core voltage.
So don't add voltage yet.
Just up you o/c to 875/1200 , then 900/1200
Without voltage and test. Then do some reading of reviews of 6850's at Techpowerup and other places and see what they get for o/c without voltage.
Yes, games are more GPU dependent than CPU, cept RTS. However possibly since your playing WoW a CPU OC would help a couple FPS. I've seen a 4.0ghz i5 give improvement to fps. Not by much, but at most you'd see like a 1-4 fps increase. But yeah, since your playing an MMO I think a cpu oc MAY help. Not sure though.