superawesomeALVIN :
Deehomes :
For the price of a 4790k you could get a GTX 970 which would be a much better upgrade.
I've already planned to get a GTX 960, it's a separate budget.
I mean no disrespect, Sir - but I think you may be underestimating your 4670's power. This CPU can cope with SLI of the heaviest graphics cards; it will not be the bottleneck until years to come. As Mr.@de5_Roy pointed out, the sensible solution would be to wait until Skylake - perhaps even a bit longer.
Granted this is a gaming PC all of your money ought to be spend on a GPU and a quality PSU now. Unless you are extremely unlucky and your specific 4670 unit is of inferior quality, I fail to find any coherent and sensible reason to upgrade your CPU. For the money left over from not upgrading the CPU, you can get a 970 or even a 980.