How long did it take to get stable, then? How many BIOS flashes did you do? I know I've had to flash my BIOS 4 times, and I still don't have my memory running at it's rated speed.
To be fair, the OP was asking about 7700K/Z270 which is stable and mature. He's not asking about any future Intel chips, because you know what? No-one knows what's happening there. Speculation and off topic ramblings on your part in this thread.
For the hard-of-thinking:
Ryzen is new and shiny. It has problems. It isn't totally stable with high memory speeds. It sometimes does the whole black screen nonsense. It sometimes doesn't cold boot. It's not as fast on single or dual core programs like games (see the thread title? Yeah..). Heck, some boards are shipping with BIOS that have totally broken temp sensors which totally screw things up. Windows still can't cope properly with all those cores.
i7-7700K has been out for ages, and the Z170/Z270 boards have been out even longer, so even the shipping BIOS is going to work first time and be stable.
You may note I have a Ryzen chip, and it hasn't been a simple job to get stable. On my i5-6600K@5GHz/Strix Z170F Gaming I used to sit down and fire up my favourite games of an evening, and they ran like a champ. For the past few months I've spent more time in EZFlash, in forums, and waiting for the PSU to discharge after another black screen that's freaked the machine out and needs a totally cold boot. Finally it's pretty happy, with compromises.