motherboard - New desktop won't POST

I've just built a PC, and for some reason the motherboard won't POST and boot the OS. I can hear/see everything get power and but nothing happens.

I have pulled the RAM to see if it's bad and it still won't work. I do however have an onboard video card and an AGP video card in, no mouse/keyboard hooked up.

Could any of those have anything to do with it? Or any other troubleshooting steps I could try?

Answer

Double check your power supply connections. I know it sounds stupid, but twice now I've built PCs and couldn't get them to post (though all the fans would spin up). After disconnecting and reconnecting all the motherboard power connections, and reattaching, the system came alive.

Sounds dumb, but worth a try.

Also, disconnect every peripheral (PCI cards, drives, everything) until it posts.