OCed my 4850, have an issue

I OCed my 2 4850s using the catalyst control center. I bumped the GPU from 635 MHz to 700 MHz and the memory from 993 MHz to 1060 MHz. I was pretty excited about it and wanted to try it out with crysis. I loaded up the last level on crysis, which seems to be the one that is the biggest test for your comp. It loaded and a few seconds into gameplay i get a gray screen and my computer just turns off, tried it once more and it froze up.

Im thinking this is a voltage problem, thoughts?

With such a low over clock i doubt its an voltage problem. Id suggest you try and use a benchmarking utility first and see if it does the same thing with that, then if it still does it try and pull the clock back and see whats stable and wont cause your system to do what its doing right now. And also keep an eye on the temps and make sure they dont get really high. I try to keep temps for all the cards i had and have under 68c with any overclock.

Also it could be a bios lock and it wont let you get such an overclock it would be best if we had all of your system specs so we could help you out better.

If it's not an Asus Top 4850, you probably won't be able to do 700 stable, possibility but just throwing it out there. Sounds dumb but try 675 first.

I can do 695 on a Gigabyte, not exactly stable, but more stable than without OC (I suppose it has to do with TDR and the OC'd card being faster, therfore less likely to incur TDR delay). Using Accelero S1 rev. 2 and a 12 cm fan blowing upwards (I hung it on a cord just under the heatsink), I go from 35-38C idle to 41C when ALT-TAB'ing into Windows, so I suppose no more than 43C in-game. I could probably handle the magical 700, but I'll need to see. My Auto-tune OK'ed it, but later proceeded to OC the memory instead, so I ended up with a 695/1148 instead of a 700 with a more modest memory overclock.

I suppose if I adjusted the cord angle and used a more powerful fan, I could get better, but this Xilence 12 cm is rather silent and when the fan blows directly on the heatsink ribs where they don't have card plate above them, then it helps quick dissipation. If I directed the stream on the GPU itself, it would probably be cooler as a result, but dissipation could hurt. However, the memory and power circuit cooling should also benefit if it gets a direct stream of air to whip the heatsinks. So I might as well try and see where it goes.