What is the "Amd Quad Core CPU" you got? I do not believe the old Phenoms were compatible with DDR3. Since you already have the CPU i would suggest the 790FX or 790GX chipset with the 750SB. I would go for Ati over Nvidia so you can Crossfire in the future. Either card will max out a lot of games out there right now, but the 4870x2 would be a better investment for the future or you can get a 4890 now and add a second once later on.