Sorry for the long post but hoping you guys can help me 
A little while ago I spent some pennies upgrading my old system but Ive got a niggle that I want to get sorted.
I bought the gtx as a first upgrade and it ran fine with no issues at all.
A couple of months later I upgraded the mobo/cpu/ram from an A64x2 4400 to the i3 @4.02ghz bundle from ocuk. Super happy with the speed increase and all went well.
I soon found however that when playing games I would occasionally get texture corruption to varying degrees. Sometimes it would just change all textures to shades of purple but everything else was still clear, other times it would be complete corruption and nothing would be visible on the screen.
Alt tabbing back to desktop generally solved the texture corruption, but not all games support it and the only way to recover would be to alt F4 and lose anything that wasnt saved.
Whilst googling for the error two common sources were identified, overtemperature and lack of power. The card rarely gets above 65-70°C so that leaves the psu.
I have an OCZ modstream 520w, has always served me very well, however it is pretty old now. I read that the max draw on the gtx260 216 is 339w and the cpu is 110w, Ive run it with all but one HDD unplugged (normally have 3) and all case fans off so I think I should have enough juice, the PSU label says its good for 620w continuous peak for 60 seconds. Its still possibly borderline though. How could I check if the gpu is running low on power?
The error seems to happen at random, sometimes I can play for hours and nothing will happen, sometimes it can occur after minutes. Ive tried turning all graphics down and it still happens. Ive tried underclocking both gpu and cpu and it still happens. Cleaned out and updated all drivers and it still happens. Disabled soundcard and it still happens. Im pretty much stuck for what to do next
Im running xp pro sp3 + all updates, latest nvidia drivers etc. Error has occurred in HL2, arma2, dragonage, bloodbowl and batman arkham asylum, I presume it will occur in any other game that I install.
Upgrading the PSU would be a good first step, however I dont really have the spare money at the moment. A full reinstall of windows is an option but a ball ache, if I were to do so I would probably migrate to W7, again a cost I cant really stand at the moment. Dont suppose anyone has a spare suitable PSU I could borrow for testing?
Again sorry for the long post but any help would be much appreciated
Beers in advance

A little while ago I spent some pennies upgrading my old system but Ive got a niggle that I want to get sorted.
I bought the gtx as a first upgrade and it ran fine with no issues at all.
A couple of months later I upgraded the mobo/cpu/ram from an A64x2 4400 to the i3 @4.02ghz bundle from ocuk. Super happy with the speed increase and all went well.
I soon found however that when playing games I would occasionally get texture corruption to varying degrees. Sometimes it would just change all textures to shades of purple but everything else was still clear, other times it would be complete corruption and nothing would be visible on the screen.
Alt tabbing back to desktop generally solved the texture corruption, but not all games support it and the only way to recover would be to alt F4 and lose anything that wasnt saved.
Whilst googling for the error two common sources were identified, overtemperature and lack of power. The card rarely gets above 65-70°C so that leaves the psu.
I have an OCZ modstream 520w, has always served me very well, however it is pretty old now. I read that the max draw on the gtx260 216 is 339w and the cpu is 110w, Ive run it with all but one HDD unplugged (normally have 3) and all case fans off so I think I should have enough juice, the PSU label says its good for 620w continuous peak for 60 seconds. Its still possibly borderline though. How could I check if the gpu is running low on power?
The error seems to happen at random, sometimes I can play for hours and nothing will happen, sometimes it can occur after minutes. Ive tried turning all graphics down and it still happens. Ive tried underclocking both gpu and cpu and it still happens. Cleaned out and updated all drivers and it still happens. Disabled soundcard and it still happens. Im pretty much stuck for what to do next

Im running xp pro sp3 + all updates, latest nvidia drivers etc. Error has occurred in HL2, arma2, dragonage, bloodbowl and batman arkham asylum, I presume it will occur in any other game that I install.
Upgrading the PSU would be a good first step, however I dont really have the spare money at the moment. A full reinstall of windows is an option but a ball ache, if I were to do so I would probably migrate to W7, again a cost I cant really stand at the moment. Dont suppose anyone has a spare suitable PSU I could borrow for testing?

Again sorry for the long post but any help would be much appreciated

Beers in advance