Hi everybody, new user here. I have tried to do my homework, but Google searches and searches here have failed to turn up any information. I have a mac pro 2006 edition with an ATI 1900XT video card. This is working just fine, and I can boot into Mac OS X and Windows Vista via Boot Camp. I just purchased a Sapphire 4870 video card. My plan was to remove the 1900XT and plug in the 4870, and always boot into Vista. I realize that since this card is not a "Mac" card I will not be able to use Mac OS X. I also expected from my reading that I would not be able to hold down the option key at boot time to select my boot drive. I figured if I had a need to get back into OS X, I'll put the 1900XT back in for that. As long as the Mac is configured to boot Windows, I thought that this setup would work fine. With the 4870 I expected that I would hear the bootup gong and then eventually see Vista start to boot up. So, with that in mind, I performed the switch last night. I removed the 1900XT and installed the 4870. I had to run an additional power lead from the spare molex connector by the DVD drive to the 4870 since it requires two power connections. The 1900XT only needs one. I plugged everything in, and turned on the Mac. I heard the startup gong. So far so good. Then, my screen turns almost completely white (a very light gray) and I see a blinking cursor in the upper left-hand corner. The hard drives begin to seek and it sounds like things are booting... however I never get to the Vista boot selection screen (I actually have two Vista installs on two separate drives, so I always get the boot selection screen to decide which drive to boot from.) I also never hear a Vista startup sound... it's almost as if it is booting into Mac OS X instead of Vista. At this point I am stumped and I'm hoping somebody here in the forum knows what is going wrong. Does my 4870 not have enough power? Do I have to have a Mac-compatible video card plugged in even if I don't plan on using it? Is what I'm trying to do just impossible?