PC freezes. what's up?

my pc tends to lock up durring game play. some times the pc will run games (oblivion, Deus, KOTOR etc) for hours with out problem. other times it locks up within five minutes requiring me to do a hard shut down. I started oblivion in windowed mode to monitor the cpu and ram usage and neither one of them maxed out.

i have.

p4 2.8ghz
533 fsb
512 ddr
radeon x1600 pro 256mb
Phillips sonic edge 5.1 sound card

i have ran hotcpu tester pro and a small graphics card stability tester. they both seemed okay. I have all the updated drivers etc.

any suggestions?

thank you.

 

What's the PSU? When the same freezing happened to my PC it was because of the cheap Q-tech power supply. Hot CPU tester said it was fine too but games didn't have the same opinion.

 

I'm not sure what the make is but it is a 400 watt. after seaching the net for the model # i think that it is a Powerlink 400 watt.

would the psu cause it to lock up or shut down? everything is still powered up when it freezes.

 

i have MSI core center and this is how it looks right now.

vcore =1.55v
3.3v=2.99
+5v=4.6
+12=11.66
CPU temp=25c
sys temp=28c
cpu fan 2556 rpm

does this help?

 

The temperatures are very low which is a good thing. However the PSU provides only 11.66 Amps in the +12 scale. Your CPU and VGA are too much for 11.66 Amps. A good PSU would provide about 18 Amps. I think you have found the guilty.

 

any recomendations for the new PSU