I bought a 2nd hand pc and after some trouble , the guy I bought it from got it working properly. It's i7 , 16gb Ram on and intel motherboard. The guy I bought it from told me that the graphics card that came with it was not compatible with the CPU . The graphics card is : gigabyte gv n730 2gi. Is it really not compatible, and if so why isn't it compatable and which graphics cards would be?