Mac Pro 5,1 (Mid 2010) GTX 770 black screen in Windows

[1800Warioman]

Hi, I've got a Mac Pro 5,1 (mid 2010) and I've put an Nvidia GTX 770 in it and I'm trying to get it to work in Windows 8.1. I got into the installation yesterday by booting off of the W8.1 DVD with the 770, but I had to exit it because I had multiple drives plugged in and it wouldn't let me continue, so now I've unplugged everything but the the drive I'm trying to install on and I believe between that time period I also did a PRAM reset by holding down: Option, Command, P and R. After all that I can't get anything to appear on screen it's just black no matter what I do, I've tried a GTX 980 too so it's obviously not the graphics card. The only way I can get any kind of picture on the screen is if I use the stock ATI Radeon 5770 that it shipped with. I'm so lost now and I have no idea what I should do.

I will answer any additional questions people may have.

Thank You

 

[Bosch14]

I don't really know much about apple computers but I would suggest you just run apples OS. So many problems arise from windows on a Mac. Yes you may be able to run the 5770 but that card may have had support for it. But I would like you to post the rest of your system specs so I could get a better idea of what the problem may be. But yeah. See if IOS works with the GPU. Remember to download the IOS versions of the drivers for it.