Vostro 460, GPU, PSU issues

I have a Vostro 460 I from work as surplus. I put a GTX 650 card in it and it was working fine. For (long story) reasons I tried an RX card in it and it didn't work so went back to the 650, but it no longer works. I have a second 650, this doesn't work either, PC boots fine but no display on any ports, no display from motherboard HDMI either. I then put the original graphics card it came with back in, this one no external power supply required, that works (but no 4K, which is why I want the 650 to work again). So the slot is OK. I come to the conclusion that power supply is no longer giving me the power the card needs, or the bios is confused maybe? Does the power supply have an internal fuse or reset? Is there a bios setting to look for? Thanks for any suggestions I might get.