The 9590 is a very, very bad choice. For basically any use. The only reason to buy a 9590 is if you want a very expensive room heater for this winter.
Now, talking seriously, the 9590 has nothing to offer. Is a very hot chip that would require watercooling. Actually, it's very close to an overclocked 8320, which you can get for a lot cheaper.
And I believe that no, AM3+ chips still have no PCIe 3 support.
And even so, nowadays intel chips are performing quite better for games. I would suggest an i5-4590k, that is the best current chip for gaming, taking price into consideration.