P4m800pro-m v 2.0 no display troubleshooting
Power off, remove AGP (video) card, unplug hard drives, cdrom, and remove all PCI cards. Unplug everything but keyboard and power. Power on and boot.
How many beeps do you hear (one is normal)?
If none, are fans spinning?-> Is the front power light on?->
If no, then try different power supply, if that doesn't get beeps, then motherboard is probably bad.
If you DO hear beeps, make a note of how many, then power off and replace AGP card. Power on. Do you have display, or do you hear beeps? If you have display, power off, reconnect hard drive(s), power on. Still working? Then power off, replace cd-rom, and power on. Still working? Power off, replace PCI cards, and power on. Still working? Then you fixed it. ;>
if it stops working after reconnecting or reinserting something, that something is probably bad. Leave that thing out, and keep going.