For mini-ITX (in the living room), wouldn't the 35W i7-6700T be a cool option too?
In that case why even buy an i7 over the i5? Another way to look at it is going from an i5-6600K to i7-6700K just adds a bit more cache, HT and slightly higher clocks. Paying a bit extra over the i7-6700K adds 2 more cores. What do you think is going to matter more over the next 5 years?
1) $110 extra to get HT + 2MB cache and slightly higher clocks
2) ~ $80-100 extra to get 2 more cores that have HT and even more cache?
You are right that if power usage is a key factor and you want this rig in your living room, don't want to OC, i7-6700k is a safer choice. Having said that I don't think people are picking 5820K over 6700K just to justify their purchase. Even for someone who doesn't own either, it's not a clear slam dunk for the 6700K for now imo. I will say that some people buying X99 sometimes have the urge to buy $400-550 boards which completely destroys the value proposition of the X99 platform. In that case 6700K will start to pull away significantly in terms of bang-for-the-buck. I've seen some people buy a 5820K with a
$550 board which is just absurd and a complete waste of $. I feel like those boards are made specifically for 5930K or even 5960X.
However difficult the choice is now with 5820K, it's only going to get worse for 6700K if Intel launches Broadwell-E in Q1 2016 and it's going to get ever harder to recommend the 6700K once Skylake-E launches in Q3/4 2016 if the overall platform premium will be just $100. I foresee Skylake-E overclocking well and running cooler than 6700K OC since it'll have solder and better binned chips. There might be a 200-300mhz disadvantage at the top speeds but from nearly every review I've read, 6700K OC is hitting 80-92*C when all the CPU is maxed out and that's on great coolers like Noctua NH-D14/15, Corsair H100/110i. These temperatures are probably fine and won't kill the CPU since Intel tends to rate them to 100*C but still, sounds like the use of TIM, no matter how good the TIM is, was a low blow again!
Maybe Intel has a cunning plan to get more PC gamers to move to the workstation platform since they make more $ selling chipsets on those boards than they would on Z170.
Also, I think a lot of gamers are not ready to discount DX12. If DX12 games come through, we could start to see 6-core CPUs provide a tangible advantage over quads over the next 5 years. Consider another scenario where you have 20-50 tabs open, a bunch of Excel/Word/PDF documents for work, and you decide to launch a game. Are you going to close all of that just to play a game for 1-2 hours? With a 6-core, you probably don't even have to think about it.
I just think a lot of budget/younger gamers are going to pick the i5 series since they are more likely to allocate the savings towards a better monitor/videocard. Someone looking for an i7 is probably not so much concerned about budget and if performing work on their computer is more likely to consider spending just a bit more for the 6-core. I think the i7-6700K is overpriced for what it is. I feel like Intel should have clocked it at 4.4Ghz or maybe allowed all 4 cores to hit 4.2Ghz on all motherboards. I guess they are saving it for Kaby Lake.