The Stoned Philosopher

Just want to get someone opinion on this problem ive been having with my new comp ive built several weeks ago (specs here: http://420.marijuana.com/showpost.ph...2&postcount=10 ).
Ok here is the problem, my pc works fine for a few days then all of a sudden it shuts off. The power button wont respond and wont reboot even though the led on the mobo is green showing its in standby and getting power. Then labout 10 minutes or so later it reboots itself. I dont think its a overheating problem since my average cpu temp is around 30c idle and 40c at max, the mobo is around 35c most the time.
I just need confirmation that its the psu since the psu i got is a generic one that came with the case.

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Beyond a critical point within a finite space, freedom diminishes as numbers
increase. This is as true of humans in the finite space of a planetary
ecosystem as it is of gas molecules in a sealed flask. The human question is
not how many can possibly survive within the system, but what kind of existence
is possible for the who do survive.
- Frank Herbert

The Stoned Philosopher