Let's wait for the final game and inevitable patches and AMD/NV GPU driver updates. All of these things should improve performance and stability. Having said that, I do have 2 comments:
1) It's strange to complain that an i5 2500K series CPU is starting to severely bottleneck 2016 GPUs in cutting edge
2H 2016 games, especially because by January 2017 this very CPU will
6 years old. It should not be too expensive to sell the i5 2500K + mobo + DDR3 memory and upgrade to even an i5 6400 + Asus Z170-E/A or Asrock Z170 Pro, etc. When considering the total cost of ownership (TCO) over those 6 years, the upgrade will be dirt cheap and an
i5 6400 with BLCK overclocking can achieve 4.5-4.6Ghz. There are plenty of examples already where an i5 2500K, even when OCed, is bottlenecking modern GPUs.
2) It's somewhat pointless to discuss stock performance of the 2500K which runs at only 3.3-3.7Ghz but can be overclocked up to 5Ghz, with 4.5Ghz easily achieved on a $20 CM 212 Evo style CPU cooler.
In general, it can even be stated that an i5 6600K @ 4.6Ghz is not
that future-proof CPU for next gen modern titles. This idea that i5s are just as good as i7s and that HT is useless for gaming has distorted the reality and people's expectations of i5s, and unfortunately this wrong information continues to be spread on various forums over the last 6 years with no end in sight.
i7 6700 stock vs. i5 6600K @ 4.6Ghz:
https://www.youtube.com/watch?v=f9cVxka2fns
At the 0:50-0:55 second mark, in the
Witcher 3, i5 6600K @ 4.6Ghz has
1 core at 92%,
2 cores hitting 95%, 1 core at 100%. In contrast, the i7 6700's cores are generally hovering at the 60-70% range in the same scene.
At the 1:30-1:32 minute mark, in
Crysis 3, i5 6600K @ 4.6Ghz has 1 core at 80%, 1 core at 84%, 1 core at 85% and 1 core at 92%. The i7 6700's highest core is loaded to just 54%. At 1:34 mark, the i5's cores jump to
88%, 2 cores hit 91% and the 4th core is at 97%. The i7's core reaches just 66%.
At the 2:36-2:37 minute mark, in
GTA V, i5 6600K @ 4.6Ghz's 4 cores at loaded at
94%, 95%, 96% and 100%! In the exact same area, the i7's 2 highest pegged cores/threads are at only 75% and 81%, with the rest hovering in the 30-50% range.
While it is true that overall the i5 6600K @ 4.6Ghz isn't exactly severely bottlenecking modern GPUs just yet, it doesn't have a lot of headroom for next generation titles should they be even more CPU demanding. Sooner or later, we will have a $400 GPU that's up to 2X faster than the GTX1080.
Fact is, the i5, even when overclocked, was
never as good of a gaming CPU for the most demanding CPU titles as the i7 was, going all the way back to i5 2500K vs. i7 2600K era. The difference is, there are just more well-threaded AAA titles coming out now that take advantage of i7's HT, and yet the outdated myth that i5 is "just as good or 99% as good for gaming" as the i7 persists even in late 2017. Literally a stock i7 6700 is an overall superior gaming CPU than a max overclocked i5 6600K...which means an i5 2500K on the bring of 2017 is going to show its age.