I had a side rig that has a AMD A6 - 7400K APU with R5 radeon graphics. I tried adding a gtx 8800. The pc selects the r5 graphics (the motherboard) output. When I try and install drivers the nvidia installer says they could detect compatible hardware. I remember I got it to work a couple times when I reset the bios, through removing the battery but then I would lose video signal after 1-15 minutes. It also isnt listed in device manager (I even selected hidden items). My bios settings are to priorites NB pci-e and IGD on auto (that is the default).