Ursprünglicher Beitrag von: lattestonetech24 ,
Hey Andrew, Sounds like your Mac Pro is starting up properly but its not reading any drivers for your Graphics Card. Here is a link to the specifications for that Mac Pro if your right on the money about what year/gen it is: [https://support.apple.com/kb/SP11?locale=en_US|Mac Pro (Early 2008) Specs]. Take a look at the specs for the graphics card and grab one that matches those specs. From experience, a friend of mine had somewhat of a similar problem if I can recall correctly and the Graphics card that ended up working was an ATI Radeon HD 4870. Hope this helps. Best of Luck!