Right now, it is not worth upgrading. The i7-4770K won't perform that much better than the FX-8350.
The FX-9590 runs very hot at stock speed. You will need very good cooling and a motherboard with good VRM design. Sticking that chip in just any supported motherboard may not work because it'll draw so much power that it can easily burn out the MOSFET.
I wouldnt do so, if i were in your shoes look here!!! http://www.game-debate.com/games/index.php?g_id=4546&ga... games are getting heavily threaded, like this one, for ultra it says you need either fx 8350 or 3770k, so literally, in multi threaded programs they are more or less the same, and all games are going to be heavily mult-threaded in the close future....so no dont do so!!! instead save money for 2-3 years later from now!!!