Is it worth upgrading a I7-4770 when I have a gtx 1080

Solution
You'll probably get a minute bottleneck in the most demanding titles of all time, but besides that you should be fine. I wouldn't upgrade until Kaby Lake comes out.


Perhaps I'm missing something (great work btw) but you haven't addressed screen resolution anywhere. As we know higher resolutions move the bottleneck back towards the GPU, whereas lower resolutions towards the CPU. That's why it's always the first question asked. Note that I run at 1440 and with an unlocked framerate I can smack 99% on my GTX1080 with only 80-90% on my i5 (looking at it right now) which is OC'd to 4.4Ghz. This is on FF14, I can try the Witcher later on and see what it does since it's a more mainstream title. Actually curious to see.
 


It's no worries, thats why we all come here to share our knowledge. That being said more and more games are demanding more from our CPU's, I shudder to think that very soon I may have to do the full platform upgrade again sigh. Here's to Zen being amazing!
 
Ah, I see I've received the famous double post! Anyhow to further, some unofficial testing in The Witcher 3 at Ultra, no Vsync, unlimited framrate(minus Hairworks) settings I got the following:

1440p 99% GPU (afterburner), 70%-80% CPU
1080p 96%(dips)-99% GPU (afterburner), 85%-99%(spikes, mostly on Core#2) CPU, spikes coincide with GPU dips.
720p 96%-99% GPU(afterburner), 95%-99% CPU, all Cores, #2 pegged.

All drivers up to date, CPU @ 4.4Ghz, GPU at 1823Mhz boost, stable.

So it seems that at 1080p a minor bottleneck presents, you are correct. Also it seems Core #2 is slightly more loaded than the rest, its peaks were reflected in game as i little judder. At this time I'm assuming this may be the core used for physics as it definitely coincided with running, jumping actions onscreen. This definitely has implications for people running 144Hz monitors. I run 60Hz Vsync so it's no issue for me (yet).