My computer starts just for a few seconds before turning off

[ADT]

Hello Facepunchers

I have a serious problem, and a big one. Like the title already said, my computer, recently builded (with my new ASUS motherboard), starts correctly just for a few seconds before turning off completely. I tried to put off, one by one, some power cables to see any results, but nothing.

My computer is composed of:
Fractal Design Define R2
ASUS P5QD Turbo (The LED on the motherboard glows green all the time)
Akasa Freedom Tower CPU Fan
Pentium Dual Core E6300 processor
4GB ( 2X2 GB ) DDR2 RAM 800Mhz
PNY GTX 460 1GB XLR8 Overclocked
1xHDD Western Digital Black 1TB + 1xHDD Western Digital Green 500GB
Antec TruePower New 650W PSU

Thank you in advance, for your help

[editline]29th October 2010[/editline]

My only assumption: the cable, from the button on / off of my case, is defective

[ADT]

I tried several times (since the beginning, because I have never used my new computer before) but I still get the same result. I explain myself:

-I turned on my PSU
-The computer starts, with all of the components
-And 2-3 seconds later, the computer is turned off completely
-The motherboard still glows green from its LED.

So you think, it's because of my CPU/CPU fan?

[editline]29th October 2010[/editline]

PS: I just built my computer in the late afternoon, today.

[Soda']

If you think it's the case cabling, detach the power wire from the pins and touch the two pins together with a screwdriver.

If the power button is defective(guarantee you it's not), it'll stay on.

This symptom can be caused from a variety of things including a dead/dying power supply, a dead motherboard, things not being plugged in correctly, etc.

I've repaired two computers where this was the case and it was due to the motherboard being fried. I hope you wore an antistatic writstband or touched a ground before working on assembling your computer. Because it was recently assembled, it is most likely you don't have everything plugged in that you need to.

[ADT]

I had a (already) defective motherboard (MSI P45T-C51), a month ago, when I wanted to build my computer.

[Soda']

[QUOTE=ADT;25727610]I had a (already) defective motherboard (MSI P45T-C51), a month ago, when I wanted to build my computer.[/QUOTE]

List the connections to the power supply you've already made-

ex:

Power supply to motherboard(24-pin)
Power supply to motherboard(4-pin)
Power supply to video card(molex/6-pin)
Power supply to hard drives/cddrives/etc(molex/SATA connectors)

Do you get video when it starts up? Can you see the BIOS display anything? Does it not POST?

[ADT]

The thing is I could not even see anything on the screen, before the PC shuts down completely

[Soda']

[QUOTE=ADT;25727708]The thing is I could not even see anything on the screen, before the PC shuts down completely[/QUOTE]

Could be the power supply, motherboard, etc. You're not getting a POST beep or series of beeps which makes me think it's your power supply/connections or your motherboard is /really/ dead.

Not much else can be done unless you have replacement parts to test the parts you've got.

[ADT]

The power supply is okay, when I tested on another build (when I built for first time)
The new motherboard seems to be okay though
I don't have sound from my case because I didn't plugged the small sound card

Someone from a french hardware forum said it could be the graphic card. He has got a P5Q Pro, said I should put the monitor cable in the second "outlet" (Don't know how to describe this in english) of my GTX 460