it depends on what is adequate for you.
No it doesn't! Some seem to think it is their
opinion that determines the
technical specifications for proper cooling. That's hogwash nonsense - if not total arrogance! The manufacturer determines that based on design, and the physical characteristics and properties of the materials used in construction. Neither you nor me get to decide what those specification are - and I haven't in this thread either.
What is adequate for you and me is a totally separate thing that may, or may not apply to others. If a Intel
8700K is pushing 70°C when taxed, and Intel has specified a maximum Tjunction temp of 100°C, then it is a technical
fact that that CPU is getting adequate cooling - even though you (and me) may prefer to see it never sit above 60°C for more than a couple seconds.
Just because a person's "opinion" may deem 70°C inadequate, that does not make it a technical fact.
Nor does sitting at 70°C automatically imply the CPU cooler does not "work" or is inadequate. If the case is not supplying a sufficient supply of cool air flowing through the case, then it is either a mismatched case for the components inside, or case cooling is improperly set up - either scenarios indicate a failure on the part of the user, not the CPU cooler.
Even the most efficient air cooler found in sneekypeets tests is ineffective at properly cooling the CPU when flow of cool air through the case is inadequate.
Now if your personal opinion dictates that your CPU temp must never breach the 30°C threshold (as an arbitrary example), then that's fine. You are entitled to your opinion and I personally have no problem with that. And if you are shooting for lowest possible, that is fine too. But understand that is for bragging rights. Do not pretend that personal opinion applies across the board for everyone. For if that were even remotely true, there would be 100s of million of stock Dell, HP, Acer, Lenova and Apple unstable and/or throttled computers out there over heating and dying prematurely. And that is just not happening.
Neither are there millions and millions of AMD or Intel processors that come today with OEM coolers being recalled because their coolers don't work or are inadequate. That's not happening either.
Would I accept my 9700K sitting above 70°C for more than a few seconds? NO! But that's just my personal preference. In fact, when my temps start sitting above 60°C for longer than a few seconds, I start to investigate my cooling. Typically, it means I need to clean my filters. And typically, my temps sit well below 40°. But there are no expectations my CPU will run better, be more stable or last longer running at 40° than it would at 50°.
***
Big fans are a tough sell these days, as most people prefer aesthetics over performance.
Huh? Aesthetics over performance? And "most people"? Ummm, no. What does fan size have to do with aesthetics? Are you saying an 80mm fan looks nicer than a 140mm fan? Or that a fan that looks nice can't perform too?
In the old days, cases typically came with 80mm fans (or often just one 80mm fan). Then 120mm became the norm. Today, most are 140mm. Some are even bigger. And I don't see where aesthetics come into play - especially since most people don't gawk in wide-eyed wonder at the interior of their cases. And, or course, larger fans are often preferred simply because they tend to be quieter since they can move the same (or more) amount of air while spinning slower - thus quieter.
Okay. 
