every good video card I've run into will operate at a default VGA mode, 16 color, 480x640 pixel, expecially at boot in the B/W mode so you can get into "setup" BIOS, where I think your problem might be. Get a cheap used video card and check BIOS out. Perhaps the mobo AGP slot is bad? No fan power means no +12 to card.
i recently bought a p4 3 ghz with an ecs motherboard and 1 gig of pc2700 ram from the previous motherboard, i installed it on my computer that was previously running an amd 2600 with a gigabyte motherboard on it with no problems, but since i installed it the computer will run and it looks as though it checks the hard drives and cdroms, i have a 450 watt power supply, so power should not be a problem. but the monitor will not display anything, i put my amd motherboard back in and everything works fine, my video card is a 5900xt and it runs fine on the amd but on the ecs motherboard the fan will not run which probably means no power to it. could it just be that the agp slot is not working correctly the motherboard states that it supports it.