I built a new system a couple months back and noticed when playing graphic intensive games I would get glitches on the screen. Recently I purchased Left4Dead and everything runs fine at first. After playing for about 20 minutes the graphic glitches get more and more common. Eventually My system just completely powers off. This only happens in Left4Dead after long periods of play. Is it possible my video card is defective OR is just overheating? Ive read that the 4850 has heat issues and I installed a third party heat sink.... maybe I didnt install the heat sink properly..... anyway I ordered a second 4850 from a different manufacturer just to test it out and determine if the original card is the issue or if its something else..
Just for reference, my 4850 idles at 40C with the stock cooler (though the fan speed is set to 55%). The original cooler without fan speed mods idled around 70C. It doesn't appear your new heat sink is doing its job.
The third party heat sink cost $50 and was professionally installed. I dont remember the brand name. Anyway this third party heat sink comes with a fan control thats mounted to the back of the PC. Ive checked the settings and its set to max. Do I also have to go and alter the fan settings from within windows?
I didnt overclock. The heatsink I had came with an external fan speed controller. That was cranked to the max. What I didnt realize is that I had to also bring up the fan speed from within the Catalyst control center in order to make the fan go at full blast. Prior to doing that I think the fan was going at maybe 25% of the speed it was supposed to be running at
I also experienced the same problem with Obvilion(after i upgraded Catalyst driver to that available from ati website)... So i changed back the catalyst driver to manufacturers version. Then problem solved..
I think, catalyst driver other than manufacturers doesn't help regulation of temperature(control fan speed auto). Also when HDR is enabled in games.... it doesn't work well... works good even with 16x Anti Aliasing.