dual GTX 1080's

[scu44]

I have an I5 4670k oc 4.6gb with a Samsung 4k monitor. Would dual 1080's in sli be okay or would it bottleneck my CPU?

 

[Luminary]

The only reviews and discussions of two GTX 1080's in SLI I've seen have been using the i7-6700k. Can't say for sure since I've not seen a review for how your CPU would hold up, but I'd wager you would see some performance issues.

ex.

https://www.techpowerup.com/reviews/NVIDIA/GeForce_GTX_1080_SLI/3.html

 

[WildCard999]

With a high OC and seeing that the CPU has 16 PCI lanes (same as i7) I would say it's doable but the only way to know for sure is to test it.

 

[geofelt]

Some games are cpu limited, and some are graphics limited.

In the mix, here is a tv, not a monitor.
At 4k resolution, the tv will probably limit you to 60Hz.
The faster refresh numbers claimed are for 1080P
If graphics is really your limiter, then I suggest a titan X pascal for fast action 4k gaming past 60fps if your tv is capable.
A single strong card plays better, avoiding screen tearing and non support from some games.

As to the cpu, your processor with the overclock is about as good as it gets for gaming. Upgrading to even a well binned I5-6600K @4.8 will not be a noticeable upgrade.