I upgraded to an Albatron 7900GT a while ago and at first everything was fine, glxgears ran at around 16000fps, games ran great everything was sweet. Then one day I noticed Nexuiz was running really slow, like 15fps kind of slow. Checked with glxgears and now it's doing like 4100fps...
I'm not sure what triggered the performance drop, it was around the time of the 2.6.17 kernel release but at the same time I removed 2 case fans which caused the CPU and motherboard temps to rise around 10-15C (still not running too hot though) and added a couple of hard drives. I figured the problem could have been the power supply, with the vid card, 7 hard drives and a dual-core CPU I figured it was a fair idea so I upgraded to a Antec Neo 550W but same problem. I've ordered a Zalman VGA cooler that should be arriving any day now to eliminate temperature as the problem but it's not here so I can't rule that out yet.
With some playing around I've established that if I turn my comp off for a while and turn it on it works for a little bit. nvclock (CVS code - some 7900 support) reports the card temp at around 55-60C and it'll run at full performance but after a short while it drops back to running like crap and nvclock reports the temp as -81C :/ Some other info, nvidia-settings reports the core temperature of the card as 291C, obviously that is wrong. With my old 6600GT there was 2D mode and 3D mode and to me this looks like it's crapping out shortly after switching to the 3D clock speeds but I think I read somewhere that the 7900 series didn't switch like that, runs at one speed all the time but I'm not sure about that.
Anyone have any ideas what could be causing this? The card ran fine for a few weeks so I don't think I could take it back as DOA because it wasn't. I have a pretty big case and don't think I would have bumped it at all when I was adding hard drives or removing any fans but I've checked that it's seated in the PCIe slot correctly and even moved it to the other slot (SLI mobo) but same deal. I'll find out if it's cooling either tomorrow or if the fan isn't delivered today next week but if anyone has any other suggestions I'd love to hear them.