I just installed windows 10 on my 5,1 with a gtx 980ti card. only snag I ran into was bootcamp installer isn't compatible with my machine on the mac side. I just downloaded the windows support files from apple, booted the machine with the windows install disk, installed, and then ran the bootcamp installer from the windows side. This only works if you have a separate drive in your machine that you can format specifically from the windows installer.