first build power problem

[stunts]

hi, I have just finished putting together my first computer.
When I press the start button all the fans including the CPU fan startup but then 2 seconds latter everything just stops.
The motherboards internal speakers make no sound.

Could this just be a faulty PSU or could I have a more serious problem?
heres the specs.

AMD Athlon™ 64 4200+AM2 Processor Retail Dual Core AM2
Asus M2N-SLI Delux Socket AM2, nForce 570 DDR2 SATAII
DDR2 2Gig(2x1G) PC6400 800Mhz Dual Channel Turbo RAM PQI
Albatron GeForce 7950GT 512MDDR3 Dual DVI/TVO PCI-Express
Powersupply Antec Neo Highly Efficient 2.2 500W
LG DVD16X+- Super Multi DVD Rewriter with Software(DUAL LAYER)
Western Digital 320G SATAII 7200 rpm HDD
Antec P180B Performance One ATX MidiTower(no PSU)

Could anyone please give me some advice?

[Freakitchen]

First of all, follow the steps in this thread. It involves removing the motherboard from the case, and connecting only the core components. It's the only way to test for a faulty component.

http://forum.pcmech.com/showthread.php?t=132409

FK

[chipdip]

Sounds like a bad PSU, if anything. I have seen some computers with symptoms like that, replaced the PSU, it worked flawlessly. Although, the PSU you are using is very reliable.

[flanzig1]

Two things are the general cause for quick shut downs on new builds: CPU heatsink not installed properly or a faulty PSU. Check the HSU first.