PC keeps freezing - help me fix my pickle/conundrum/problem

[Hexxle]

Hi everyone

My PC at the moment has quite a serious problem - when it boots up onto the dektop, after a few seconds the computer will either freeze completely, or will restart itself. Thinking it was a PSU problem, I replaced it with a more powerful 700W unit (from a 500W). I thought this had fixed the problem, because the PC lasted longer before it froze up. Also with the more powerful PSU, the PC seems to last longer on average than with the smaller PSU.

Some other details:
When this problem first started to appear a long time ago, it would only freeze/restart when under heavy loads (ie. Gaming, among other things). It is completely fine in BIOS; no restarting or freezing. When the PC is first booted up, the black screen says it only senses the PC has 512Mb of Ram, but the BIOS says it has 2048Mb of RAM (The correct amount). Tried switching the RAM with each other,(have not tried with completely different RAM in the PC) but to no avail. And sometimes when it freezes, a BSOD comes up saying "There might be a problem with your hardware or software... If this is the first time it has happened, restart your PC. If not... bla bla bla"

Specs are:
PSU: 700W Thermaltake brand new)
RAM: 2GB generic brand
CPU: Intel Core 2 duo E6750 2.67GHz
GPU: Nvidia 8800GT
MB: MSI ms-7360


Thanks

[liljim]

the very first black screen your seeing could well be your video post, meaning theres 512 megs of video memory. Thats seperate from the 2 gigs of system memory.

have you checked your cpu temps? Id make sure the cpu fan is working and see of any of the board software can display the cpu temp. You should also be able to see the temp in bios via health status, hardware monitor or something worded similar.