I really do not think this issue has anything to do with overheating. While playing pb I was running GPU-Z in the background, temperature was 52C. Tomorrow I'll do some tests (save temp. level to file and see how high it is when comp hangs up). I was thinking that this problem is linked with drivers, I have ForceWare 182.50, but for the first time pb made me reboot computer was on 182.06. Played a lil with cl_sleep 5 and no hang ups so far, but as I mentioned, tomorrow I'll test it.
Edit: cl_sleep 5 doesn't help - 15 minutes of pubbing and bah, had to reboot.
Edit2: Less than 30 minutes of play, logged gpx card's parameters to file. Comp hung up with 55C, so I'm sure it's not overheating problem. After turning comp off, graphics card wouldn't run for several starts (and that's really bothering, any clue why and how to fix it?). Cl_sleep 5, logs attached.
Edit3: Cl_sleep 0, played over an hour and decided to stop, no hang ups, highest temperature 59C. Logs attached.
Final edit: Guess what... opened the case, plugged power cord harder to gpx card (althought it was plugged in hard enough), plugged gpx card more to mobo... problems totally gone! I find it kinda strange, but at least I'm happy now that I have nothing to worry about.
edit...:
FFS, it still happens to me, and I have NO idea why, I've updated drivers lately to 185.85 and played on them just fine until today - played for 5 mins and had to reboot, next time I had to reboot was after about 20 minutes. If anyone has any sort of a clue I'd love to hear it.