I’ve had instability with my 7700k since I bought it, and 16 months of bios updates haven’t helped. Maybe this latest generation of processors just has more trouble than older, simpler designs.
Intel has been struggling with CPU performance for a decade, and has been trying to regain their position in absolute performance and performance/{price,watt} comparisons. I think that means they’re being less conservative than they used to be on the hardware margins and also that their teams are likely demoralized, too.
Possibly. I would start swapping parts around at that point. Different memory, different CPU, or different motherboard. Just 1 more anecdote, but my r7-7700x has been a dream (won the silicon lottery). It runs at the maximum undervolt & RAM at 6000 with no stability problems.