BFG 8800GTS artifacts/lockup

Hi,
Been browsing around TH for a good few years now, looks like its my time to post.
Last summer I built a new PC, the specs are as follows:

AMD X2 4600+
BFG 8800GTS OC2 320Mb
2Gb RAM (generic) -> cheap skate I know :-(
450W PSU
CoolerMaster AMMO case
250Gb SATA2 7,200RPM HDD

Ever since completion - It hasn't been totally stable with the odd lock up or BSOD. I picked up a copy of Crysis Warhead on steam on saturday and I've been plagued with lockups/display failures/artifacts all but the last requiring a hard reboot. The artifacts are mainly in textures - regular interlacing triangles are missing however from some POV's I get the shooting textures across the screen.
These artifacts can occur between 5 - 20 minutes of gameplay in Warhead. I've had a few artifacts in ARMA - shooting textures in some parts of map combined with indecently low framerate.
I'm hoping to god it's the power supply thats bottling out - attached is a screenshot of speedfan with voltage + temp measurements.

Sorry 'bout the length but I wanted to be sure to cover things.
Regards
Sam.H



EDIT: Damn lockup - have to make do with voltages only ATM - temps take 20mins to achieve. + +12V rail normally reads ~10v

what are the symptoms when PSU is going out?

Hi,
Got anew PSU today - hasn't solved the problem . Don't have a clue whats going on - played for about an hour yesterday before crash and tried today - only lasted 5 minutes. Almost certain the temps are fine and am reading about people with a similar problem. Maybe I have to wait for a patch to fix this or are there any other ideas?
Cheers
Sam