I would save my money and not go to the 4790k as you won't get a huge advantage out of it unless you are planning on overclocking the processor and for gaming there is no real need when you already have a 4770.
Ta. At least there's no mobo in the equation. Which probably makes the decision harder. But a k version and sell the non k. Probably cost you $150 to upgrade. And get 10% performance increase - from cpu only. You really wouldn't see it in games.
I just do not see the point in getting a i7 4790k right now, especially if you already use a 4770. The only thing you will actually get noticeable gains in is benchmarks anyway. Right now the i7 4770k is better IMO, ,more so if overclocking. they have had plenty of time to tweak it and The overclocks now with z97 are getting better then they were at launch. I just do not see Intel getting any more Speed out of the Haswell CPUs on an overclock. There is a good PcPer review on the i7 4790K and their sample did not OC that well. results may vary of course. I would like to see the 4790K hit 5GHz at least 40% of the time in the near future with a newer stepping/model although i don't know if Intel does that anymore. But the i7 4790,non K, is actaully cheaper then the i7 4770k in most places so that is technically a better value if you do not OC it.
do you think i would need a new psu if i was to upgrade? I read that the 4790k is quite a bit more power hungry than the 4770.
also yeah i do want to overclock i was meant to have the 4770k but my order was messed up and they ended up sending me a 4770. i built full water cooling for overclocking and its wasted on my current cpu