My computer turns on for about 1 second then shuts off immediately

[Axxxxx]

This was my first build then when i tried turning the computer on. it just shuts off instantly I already tested it with 2 PSU but still the same thing happens. I don't think this is the problem.
I changed the RAM sticks already and the Graphics card but still nothing happens just turns on a split second then immediately shuts off.
I don't know what could be the problem is it the CPU or the Motherboard ? the CPU is brand new but the motherboard was only 8 months old. I hope someone could help me fix this problem

Here's my Specs
AMD FX 6300
Gigabyte 990 FXA UD3
Sapphire HD 7870
Corsair RM Series 650W
WD Caviar Blue 1 TB

 

[Supahos]

Reseat (remove, and put back in) the processor and see if it will boot, unplug anything you don't need to function IE, 1 stick of memory, a processor, and hard drive, nothing else. See if it will boot, if not slowly plug more stuff in till you figure out which is causing the issue. also clean the socket when you take the CPU out if u see any dust or debris in the socket.

 

[rad666]

I had a similar problem when I was putting my current system together. I had accidentally unplugged the CPU heatsink fan and the system kept going into thermal protection shut down withing a few minutes of powering up.

Once I sat a watched the CPU temp in the BIOs I was able to trace the problem.

 

[Axxxxx]

Reseat (remove, and put back in) the processor and see if it will boot, unplug anything you don't need to function IE, 1 stick of memory, a processor, and hard drive, nothing else. See if it will boot, if not slowly plug more stuff in till you figure out which is causing the issue. also clean the socket when you take the CPU out if u see any dust or debris in the socket.

I tried changing the RAM's already, and removed the processor and put it back in i change the thermal paste too. but still it won't boot same thing always happens just turns on for 1 second then turns off. I just checked the CPU socket right now there's no dust or anything in it.
So i guess it is the Motherboard. i haven't tried changing the CPU yet.
but im not so sure which one is defective.

 

[pepesapo]

i have the same problem right now.. my processor is brand new, the motherboard is not.. the person who gave me the motherboard told me it had problems, but i dont know now.. because i read a few articles in the internet and most of them says is the cpu.. i dont if that is my case but i would like to ask if someone knows if the problem can be the motherboard