Asus P5N-D won't power up

Hey guys, I'm new to this so humor me.
I'm trying to build a system with:
-Asus P5N-D motherboard
-Intel E-8400 dual core processor
-Corsair 2x2GB DDR2
-Ge9800 graphics

I put the cpu in place, installed the memory, and power supply but when i hit the power button on the chasis (which is connected), all i get is a short burst of power and then nothing. So, what i see is that the fan turns on for a second and then stop. The little green LED is on so i know there is some sort of power getting to the board.

I've checked the power supply by itself by jumpering the green status line to gnd and everything checks out ok with that.

I tried clearing the CMOS. Same results...

I don't have another motherboard readily available to swap out the cpu, but is there anything else I could try to figure out what the problem is?

I haven't plugged in the video card yet, will that make a difference? Things didn't seem to be working so i didn't want to damage it by plugging it into a potentially bad motherboard.

Suggestions???

I haven't checked the board but if it has onboard Video connection then No.

I have had faulty CPU fans cause the entire Motherboard not to POST so you could disconnect that connector, then try turning on (if it actually stays on then turn it off straight away, and replace the CPU fan.)

Failing that, I would say that you need to start disconnecting other components (HardDrive etc) and possibly even BenchTest the motherboard out of the case.
You can find more guidance on how to do this here: Tutorial: No POST (Power On Self Test

I figured it out. The video card needs to be plugged in to the motherboard for everything to power up.