Okay so my computer stays on for about 4-6 hours and always blue screens sometime between that period no matter what I do. I'm able to play games on it fine and they don't cause it to crash. Time is what seems to make it crash. I have two fans in my case and three if you include fan on heatsink.
CPU: Phenom 9850 2.50 ghz quad core
Power Supply:Ultra LSP 550w. 135mm fan. Input: AC input voltage: 115/230v. AC input frequency: 60/50hz.
Ram: 2 sticks of hynix 1gb 2Rx8 pc2 - 5300U - 555 12, 2 sticks of hynix 512mb 2Rx8 pc2 - 5300U - 555 12 (All the ram is recycled from my old computer but work)