Re: software or hardware problem?
What are your system specs?
Sounds like your psu is rapidly on the way to being a door stop. Low power/sudden drop outs will be causing bad data sectors on the HDD hence checkdisk wanting to run all the time.
I doubt a video card has caused the problem, I would suggest the psu was never 100% and the video card has "tipped it over the edge" so to speak.
Try another psu is probably the cheapest option.
E8600@ 4.25GHz, 1.325V | Thermalright Ultra 120 eXtreme + Scythe Slipstream 120 | Asus Rampage Extreme| 4GB Corsair 2000MHz 8-8-8-24 @ 1600 6-7-6-24| ASUS 9800GTX| Pioneer 18X SATA DVD-RW | 320GB + 500GB WD SATAII | Antec True Power Trio 650W | Thermaltake Sonata | Vista Ultimate x64 SP2/Win7 Ultimate