I dont know if this is in the right section but here I go,
When ever I start windows and the windows Vista logo comes up and shines it lags while doing that, as soon as I get on to my desktop My mouse lags all over the place then after a while it stops but I can't play anygames with out stop and go lag even in single player with all settings at low. This never used to happen to me it just randomly started up. I scanned over and over for viruses,etc. but have found none. I sometimes get The USB Storage thing can be plugged into a faster port or something like that and, rarely just sometimes get memory errors and once and awhile i get the plug and play sound that i think tells you a a device has been plugged in and unplugged,
I also noticed that somehow DX10 has gotten on my computer but I never downloaded it and installed it...And I know that the 6 series cards made by nvidia do not support DX10.
I need some help on this I have tried everything,
EVGA 6800XT (256)MB Ram
1 IDE 120 GIG SEAGATE HDD(Main with vista Installed)
1 SATA 500 GIG WESTERN DIGITIAL(SECOND)
430 WATT THERMALTAKE PSU
2 OLIPTICAL DRIVES
INTEL CORE 2 DUO (2.8GHZ)
I had similar problems when I got my GTX 260, After doing some simple tests, like various games and benchmarks and such, I realized something was very wrong, I opened Everest and it said my card was running @ 1X instead of 16. I had to RMA the card, the new one performed normally. Grab GPU-Z for kicks and giggles to check yours.
Either way your card may need replaced. Hopefully you registered the card, otherwise you may not have a lifetime warranty.
Edit: Nvidia Control Panel will give you the same info as GPU-Z, just click on System Information on the bottom left.(Scroll down, its the last one)
It was just a guess. myself, I think it probably is just your card crapping out. So its a good thing you bought a replacement. Best way to find out would be to try your 6800XT in another computer, without opening the the new card incase it works in the other computer. I also recommend using Driver Sweeper to clean the old drivers prior to installing the new ones.