Hi, Just tried to install a PC graphic card 5770 instead of an apple nvidia 8800gt. I was told that I should be able to use any pc card in a mac, but there won't be a boot screen... In my case, I got no picture at all... The cooler was working, that's it. I took the 5770 out, put the apple 8800 GT back in, and now I don't have the boot screen anymore... How come the pc card wasn't working and why don't I have the boot screen now? Any ideas? Thx.