Upgrade i5-4670k to 7700k to go with GTX 1080

No, I do not think $600 is worth the small performance increase. Certain games/situations like you mention are going to be processor limited with a GTX 1080, especially in heavily threaded titles, but unless it becomes unplayable I see no reason to move beyond a very capable Haswell i5 processor. The memory speed will not make much of a difference.

In regards to SLI, remember that it isn't well supported in a lot of titles and will offer little benefit. However assuming a title with good SLI scaling attempting to drive 4k resolutions or something similar it is likely you would want as much processor power as reasonably possible.

SLI with Pascal -- wouldn't do it.
The support for sli is decreasing and Pascal on top of it scales especially bad.

As for the performance upgrade:
3dmark puts maximum load on all threads.
A game does not.
Look at the difference in games between the 7700k & the 7600k. The 4670k is 20-25% less potent in terms of FPS tops. Overclocked more like 15%

That would be my view. Kaby Lake does not offer much improvement, and the extra threads of an i7 vs an i5 don't usually mean much in video games.

I personally wouldn't spend $300 (net) for it. You won't see enough improvement to justify the cost.

You need to weigh several factors when making this kind of a decision.
Are these the only games you play?
How well optimized are these games (will an i7 actually provide any improvement in this specific title or does it have FPS drops regardless of CPU hardware? This is a rather common problem.)
Are there certain settings that you can decrease in these games to provide more acceptable levels of performance without a significant or noticeable reduction in quality?

Overall this situation is to be expected given the GPU you purchased. A 4670K even when overclocked is going to somewhat bottleneck a GTX 1080 in CPU intensive titles. But $300 is pretty steep.

20% only sounds much. if you're at 70fps, you're at 54 instead. and that's not always, that's sometimes.
consider this analogy: for example the GTX1060 is as strong as the (second) strongest card of the last series, the 980. your CPU is another generation older, so it's more like a 780, but since it's not the top line, more like a GTX770, while the i7 is top of the line, like the GTX1080. in terms of GPUs that would be an performance increase of 180-200%. that's justifiable. the 20% of the 7700k vs the 4670k that's not worth 600$

also since your 4670k is overclocked the difference it's more like 15% (probably even less)
for 600$ that's kind of a small gain.


for 300$ that's a different story.
as even upgrading to 4790k will cost that much.

I kind of dislike the notion that the i7 won't show any improvements in certain titles.
yes, some games don't support hyper threading.
but those benchmarks have only the game running. Usually, I don't know about you, I have a bunch of other stuff running as well, as a browser, music, maybe teamspeak, steam, my mainboard utility, my mouse software and so on.. which all adds a bit to the cpu usage. granted it's not much but the sheer mass can make a difference. but this isn't something you can see in benchmarks.
however I empathize that it depends on your actual usage and that many people will not be in a scenario where the i7 makes that big of a difference.

I suggest you just try it with the 4670k and if you come to the conclusion that you need more CPU juice you can upgrade anyway

Not worth the switch. If you really want an i7, just go with a 4790k. Not sure it is really worth it, unless you can sell the 4670k, for a good price. Keep in mind that your board may need a bios update, for a 4790k.

Are we comparing an overclocked 4670k to a standard 7700K though? Without the overclock the delta in performance for some games is closer to 45% than 25%. Specifically - for example - Ubisoft games where the extra threads are used a little better, though the number of games that use the technology is slowly increasing. But all the same, if we are relying on an overclock to beat a factory standard clock that's not an apples to apples comparison. The 7700K overclocks pretty well so why wouldn't you factor that in? 4.8 seems the bare minimum stable even for those chips that lose the silicon lottery. If you are going to overclock your 4670 by 800Mhz - then let's be fair and overclock your 7700K as well. At 4.8 Ghz (which from what I've seen they all seem to do) the delta in performance is closer to 30%. The IPC improvements add up to about 12% over the generations since the 4670 (really pretty poor given 3 iterations - and the 12% is a result of compounded improvements of course), the clock adds another 15% and in many games the extra threads adds "X" where "X" really depends on the way the game is coded. But 27% minimum for a game not optimised for extra threads- and if a game uses the threads 40%+.
For me that's marginal on the upgrade. My principle for upgrading is "Offer me 50% minimum improvement or no dice" So despite my quibbles I actually agree with everyone else here. Unless you have some specific software where you need 25% improvement desperately - I wouldn't upgrade for at least another year. My next upgrade is when a good chip (not a dog and pony show like the AMD 9590) does a solid 5.0 Ghz out of the box. With Intel now being pushed by AMD's Ryzen, that day might be coming sooner than I thought a few months ago. I'm going to wait and see if Ryzen shakes Intel up and one or the other brings out a real killer CPU in late 2017. Intel might bring out a range that ditches the graphics capabilities and uses the less congested die space to either add cores or boost clock just using their existing technology. They might be pushed into getting better performance from Coffee or Cannon lake. AMD might ditch their stupid idea of low clocked R3 and R5 chips (Why AMD? Why?) and give us a 6 core 12 threaded chip that clocks at close to 5 Ghz with an IPC in touching distance of Intel's. Not going to buy now - something is brewing that will be good for consumers now there is competition in the market.