Is it possible you have a bad 6-pin power cable going to the 460? IIRC, your psu isn't modular, so you can't have the psu-end plugged into the wrong port (Yes, it has happened here, within the last 3 days lol).
If you have no way of checking that (multimeter to start, another psu, a different cable, a molex to 6-pin adapter), it is possible to to use a cable you know works from your GF's psu, if you cozy them up together (touching so they share a common ground).
You have a working mobo slot, a working vid card . . . power and drivers are all that's left. And a driver issue would give you at least a BIOS screen.