Computer shut off and only turns on for a second then shuts off again.

My computer shut down randomly last night and when I press the power button, everything starts up for a second or two and shuts off again.

It was working fine all day yesterday, but then it shut down for no apparent reason. I have had some previous trouble with the motherboard and had to have it sent in and traded for a different one(same model).

I was playing Fallout:New Vegas, (not graphics intensive for me) and my computer just shut off, like power had been cut. Then it tried to start again, but failed after a couple seconds. From then on, every time I pressed the power button, all the components would start properly, all fans and lights, then all of them would shut off. Same result every time. No beeps from the speaker and no error messages. I haven't added any new components recently either. All components were snugly in place.

Specs:
CPU: Intel i5 Ivy Bridge
Motherboard: ASUS P8Z77-V LK
RAM: CORSAIR Vengeance 16GB (2x8GB) DDR3 1600 (PC3 12800)
CPU Cooler: Cooler Master Hyper 212 Plus
Video Card: Nvidia GeForce GTX660 Ti
Power Supply: Corsair HX 750 (750 watts)
Hard Drives: Seagate Barracuda (2000GB) and a Micron Crucial m4 SSD (128GB)
OS: Windows 7 Ultimate
Case: NZXT Phantom

Things I have tried:
1. Let computer cool off completely and try again.
2. Waited overnight.
3. Cleaned and checked GPU for damage (none).
4. Took out all components.
5. Checked all connections to motherboard.
6. Cleaned and checked CPU for damage (none)
note: There were some small flakes of thermal paste on the contacts of the CPU and the pins on the mobo. I cleaned them both very gently.
7. Followed the guide here: http://www.tomshardware.com/forum/261145-31-perform-steps-posting-post-boot-video-problems
note: I tried to turn on my computer after all of these steps and got the same result.

Any ideas about what happened? I suspect the motherboard or the CPU.
3 answers Last reply
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  1. Well if there was thermal paste on the contacts of the CPU then it might have created a short so either the CPU socket or the CPU is dead. That's my theory.
  2. DMorrison, I have a similar problem. What did you end up doing?
  3. I couldn't find a definite solution to the problem, so sadly, I just bought a new motherboard.
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