Problem with new computer

[DopeaLope]

Hey, this is my first computer i've built, I have an Asus M2N-E motherboard, 1 G (2 X 512) Mushkin sticks, AMD athlon 64 processor, Geforce 6800 Xtreme video card by nvidia, SK-523 Kingwin case, Rosewill 450 W power supply, let me know if you need any other specs I forgot.

But heres my problem, everything fits correctly, but when I go to power it on, the system seems like it's only getting power for a split second, and then shuts off. I can see most fans twitch, but then go back to inactive. I've already replaced the power supply, and i'm still getting the same problem, i'm starting to think it's the motherboard. Can anyone shed some light on the subject? Any help is very much appreciated.



Edit- the motherboard DOES say it's getting power (green light is on), I have called ASUS but they didn't help.

 

[Nitestick]

check that all 24 pins of the ATX power connector are connected properly and then more importantly check that the extra 4 pin or 8 pin power connector is attached properly to the motherboard.

 

[bigbaddog]

Also check your switch-you can unplug your switch at the motherboard and cross the connectors to make it come on. Might work, but after you check all your PS connectors and rule out the switch...it's sounds like a bad mobo