Graphics card or Psu dying?

Hi there,

Recently my computer has been restarting whenever it gets a bit too graphics intense for its liking, i.e. playing graphically demanding games while multi tasking The GPU temporature is running a bit too hot for my liking, but I'm not overclocking any of my components atall. The OS (vista) doesn't realise when it's restarted so its definately a hardware problem not a software stop error or anything (disabled auto restart on stop error, no error appears).

now, my graphics card, a nice nvidia 6600gt, is fairly old and i'm willing to upgrade it (i'm looking at the 7600gt arctic cooling edition) however I'm not convinced it is the graphics card thats a problem. It could be the PSU not providing enough power, which would cause the graphics to crash restarting the pc, and would also cause overheating.

However, I have no way of telling whether its a faulty psu or old dying graphics card. all I know is the psu shouldn't have a problem, its a fairly new (less than a year) 500w, and the graphics card is old and I wouldn't be surprised if i need to replace it (its apg anyway and i could do with a pci-e now)

So my question is, any way to tell for sure whether its the psu being naughty or the graphics card? And no, the only other psu's i have lying around and much smaller and wouldn't be able to power my pc I've got a few older graphics cards lying around too, but they are even older so I don't think testing them in my rig would help?

Thanks in advance,
Technosites

thanks

hmm ok, i was looking at benchmarks and reviews on the 8 series and it would seem that generally the 7600gt comes out better than most the 8 series. my price range is 50-60£

I started noticing problems when playing eve-online, which is very graphics intensive. and today when I tried counterstrike:s max settings at 1024res is crashed instantly, but its ok now i've dropped the settings down a bit.

Thanks for the help,
Tech