CPU Problems Perhaps?

Im a gamer, and not a casual one, so this is a big problem for me. My computer broke, but i had this friend who knew a guy, who was an idiot. This idiot was selling a computer, a brand new, never-been-used computer. He was selling it for $25.

Apparently "It just didnt work at all", what the problem really was: there was no installed OS. So i got this nice(i think) Computer for only $25.

My problem now is that i when i try to play games on this computer, it likes to shut off randomly. only during games. What puzzles me is that this computer was custom built for gaming. It has a 600gig hard drive space, with slots and unused cords for 4 more hard drives, 4.1Gigs of RAM, 2 Intel Core 2 CPUs(2.40GHz), A beautiful GeForce GTX 260 Graphics Card, and a 700w power supply.

So, im confused as to why it would hut down during gameplay, although i think it may be a lack of CPU.

I can play all older games ranging from FFT(1991) to Commmand and Conquer Generals:Zero Hour, but if i play Oblivion it only lasts a few minutes before shutting down. Even minecraft after awhile will kill it. But Amnesia: Dark Decent works perfectly fine...Minecraft > Amnesia???

So as i await a response, im going to install Neverwinter Nights 1(yes, more games for a currently unstable computer ) and hope that it works correctly, because i really need my daily dose of visual heroin.

 

Have you checked your CPU temps. while playing? Run OCCT which will stress all your components at once and write real time charts up until shutdown which you can read after reboot.

 

Ran a few CPU Temperature tests.

While idle: It peaked at 60 degrees celcius but generally stayed around 52.

While playing: Pretty much the same thing, peaked at 62 and stayed around 55.

 

Your idle temps are too hot, should be under 40C, closer to 30C, but it shouldn't crap out until 80C, both CPU fans spinning properly, any dust/debris on the blades/case? I would re-apply the thermal paste on your CPU anyways. BTW, what's your GPU temps?

http://www.youtube.com/watch?v=fRRWbQUqW1Y

 

Yeah, everything working properly and clean.

GPU Temps
Idle-52 to 55
During gameplay-55-58

 

Run OCCT like I asked to completely rule out your temps please as I don't like them. Otherwise, I have no idea.