bjornl :
I would not be looking at either of those two CPUs unless there was a significant price advantage. I would look at the 8086k or as the step up a 9900k. The 8086k is the same chip as the 8700k, but it is cherry picked and so runs a little faster and might overclock a little higher. The 9900k more or less matches the 8700k in features including hyper-threading. The 9900k is clearly a superior CPU for those needing more than a 8700k, while I don't view the 9700k as being obviously superior (although it is a good CPU).
Between the 9700k and the 8700k, I like the older CPU better. It puts less heat in to your case, which you're going to have to move out of the case (and raise the temps in the room. It has hyper-threading (the 9700 does not) also it has 33% more cache per core (2mb vs 1.5mb).
The power consumption difference isn't much. Around 10%.
The overclocking will vary depending on model, but the 9700k does seem to be more reluctant to OC despite having the better thermal interface material. If you want more out of the 9700k, you're not going to get much. Thus far overclocking the 9700k has been disappointing. No review talks about this being a good overclocker despite the TIM advantage.
If you want ALOT more out of the 8086k or 8700k, you're probably going to have to have it delidded and replace the thermal interface material. You can do this yourself if you have the time and inclination. Or you can do as I did and use a service like SiliconLottery who will do it for a nominal fee.
Finally the BIG issue. For gaming they are identical for 99% of games. There is a trivial difference between them. Unless you are going to do rendering, video-editing, or other very CPU intensive work, get the cheap one and you will only give up 1-2 FPS in games at most and have an easier overclocker if you need that stuff back. Games don't use more than 1 core for most of them, VERY few use 6 cores or more. The sole exception might be the Civilization series which should benefit more cores.
When looking at other claims of gaming superiority of one or the other, remember they are comparing 1080p games which run at 200 or 205fps. Who cares about 1080p? Who cares about a trivial percentage of FPS which are both faster than a typical gaming monitor can render? Your specs indicate you are clearly going for high pixel count gaming or VR. For this, there is no practical difference in the CPUs.
Exactly, I'm aiming at 1440p and at VR with this PC. Just checked and the 8086k is around 530€ so its 70€ more than the 8700k and 55 more than the 9700k. I looked at the 9900k but its priced at 610€ and I don't really see it being worth 140€ more.
I agree 100% with everything you've said as it's what I've read everywhere. Still, being the difference just 15€ one from each other I am reluctant (i actually have already in order the 8700k waiting for the 2080ti to arrive) if I should pick the 9700k.
For the moment I'm not planning on having a huge OC or have the cpu delidded. Just boost it up a bit and that should do.
jay.wooster :
Personally i would go for the 9700K or 9900K because i'm a sucker for new tech and the thermals on the 9700K and 9900K should be lower since they are going back to soldering, which should also help for overclocking contrary to what Bjornl has listed, although the rest of his arguments are sound
As far as I've seen, although they are solded they still get a lot more hot than the 8700k and the room for OC isn't very large at this moment.
Having the latest also is a +1 for me. Even more when I'm not planning on upgrading in several years.