radeon 4870 and windows 7 not working

i'm updating a pc i built for a coworker. he chose the parts, i put it together. now i have it back and am putting win7 on it. here are the components,

gigabyte ga-ex58-ud3r mobo
core i7 920
g.skill ddr3 3x2gb 1333
radeon 4870 dual
corsair TX650

pc won't complete install or boot into a good install while the 4870 is in the machine. monitor says no input and goes to sleep while booting.

power connectors are both plugged in. 4870 worked fine on vista before i nuked that install.

was able to install win7 and it runs fine on a geforce 7200gs pci-e i have laying around.

wtf. i tried both dvi ports, and i tried installing the catalyst control center with the 7200gs plugged in and then switching the cards back, no dice. any ideas?

Make sure the video card is plugged all the way in, make sure its not catching on anything around the PCI port, I have had a problem like this with one of my other machines. Other than that I don't know what to tell ya, I am running a 4870 on W7 fine. Did you maybe damage the card upon install? or is it new? if so maybe the card is DOA.

Try installing Windows 7 without the 4870 installed. Once W7 is installed put the 4870 in, if it doesnt work by that point then you know its the videocard causing the problem for sure, that could mean its damaged. Are you running crossfire? Try running a single card at a time.

the system booted into vista just fine before i formatted it and installed 7.. but 7 won't load except with the other card. i never even opened the case until it wouldn't start.

problem solved.

put the 7200 gs in the first pci-e slot and put the 4870 in the second slot. was able to boot into windows and complete 4870 driver installation. took out the 7200 and put the 4870 in by itself and it's working fine now.