works in one pc not in other

Alright, so I just got my hands on an rx 460 4gb gpu and a 1155 mobo, with i3-3rd gen cpu, and 4gb ddr3 ram. Now this is probably one of the most complicated cases ever. So I booted the mobo + cpu + ram and an ssd and it worked fine etc. But then I tried to put my 460 in the pcie slot (I'm sure...