so 2 weeks ago i bought a GTX470 put on a waterblock left it nice and stock otherwise and had a blast playing games for 2 weeks, till this morning.

my screen was frozen but the voltage on my CPU was pretty low so i upped it a bit and it seemed to work fine, but according to the clock on my frozen screen when i came back from work it froze 2 min after i left...

now i have been fiddling with my pc for 4 hours now trying to fix this but i am unable to.

if i dont install any drivers windows runs fine, no freeze's.

as soon as i install drivers and try to boot windows 9/10 times i cant even get past the welcome screen the other time as soon as i try to stress the GPU with kombuster or anything like it windows instafreezes, if it just just freeze its self before i can even reach kombuster.

now did my card just get defective after 2 weeks of running fine or is it possible my PSU has just now degraded to much to pull my rig.

the PSU is a 620w Coolermaster PSU about 2 years old been used close to 24/7.
basic rig :

Intel core I7 920
6GB of ram in 3 module's
6 Hard drives
1 DVD drive
6 120mm silent fans
1 140mm silent fan
1 Aqua computer pump

and thats it for the power hungry stuff

i have so far try'd the folowing
clear Cmos
Update Bios
switch to other DVI output (u never know and im desperate)
switch to 2nd pci-e slot (same as above:P)
reinstall windows 7 on a different HD just to make sure...same problem :(

so i was wondering can anybody shed some light on this issue for me?
i have no idea whats causing it :(

(signature is no longer accurate btw >.<)