I just want to verify this. You said your second video card seems to have been fried, and now when you just have one video card in, you don't get any video? You say that everything else has power, but you don't get any video, does the video card fan spin?
Since you just bought the second card, and its dead, you could try to 'exchange' it for a new one. If you can do that, see if that new card works in your PC. If it doesn't then it looks like the PCIE slot might be dead. If you cant 'exchange' the newer fried card for a new one, then find another PCIE card to test your mother board in. I doubt its your PSU, its either both video cards are dead, or the PCIE slot on your motherboard is dead.
Good luck man.