No POST on bootup

I’ve built a computer for a client and it will not POST at all. I don’t get any beeps from the AMI bios, if there is one in CMOS (I’m beginning to wonder). I’ve tried an AGP and PCI video card and nothing comes up on the screen at all, zero-zip-nada. Anyone have any ideas? I’m fairly stumped.

Yes, my monitor is plugged in. 😉