Hi I have a Win7 64 bit with 600w power supply. My old Radeon card died, so I used an old nVidia card until I bought the new R9 270X card. I didn't install any drivers with the nVidia card.
When I inserted new GPU the system recognized it and I started to install drivers from the CD and the system froze up. A reboot does not show any video display. If I pull the CMOS battery it will see the card again. I've run a couple driver removal apps including the AMD one, and also deleted the C:\AMD directory. When I run the Auto Detect utility it recognizes the old Radeon card. If I try to run the downloaded driver installer it gives "Failed to load detection driver".