P4 and Athlon are 2 completely different things. but either one of them would be pretty outdated, far from extreme gaming capabilities. what kind of money are you looking to spend?
the cyberpower would be good and at a grand less you cant go wrong. and with all the money your saving you could pick up another 4 gigs of ram and have 8gigs. but that would be overkill.
my computer did this when i had a peice of plastic stuck in one of the RAM slots. so take your sticks out blow in the slots and make sure theyre seated correctly.
im guessing here but since that cpu has seen temps of 105c and the problem sounds like an unstable OC then maybe the cpu is partially damaged and is now unreliable.
ok they can either...
make a game with awesome graphics that will run on "average" computers if you turn down the graphics to look "average"
or they can make a game that looks "average" no matter what you play it on
common sense?