There is another problem with watercooling, which is that once the water warms up (which it will under sustained loads) your CPU temperature will begin to climb.
Then it becomes a game of "do I have thermal mass enough to run my job before throttling", and often it can be the case that radiators are unable to effectively cool down the CPU; but the additional water becomes thermal capacity; sometimes giving the appearance of better cooling when in actuality your system will throttle after 10 minutes of work.
Your heatsink is one of the better ones, an NHD-15 might be better but only slightly, after which point: I don't think it can be expected to cool a CPU at a sustained load with any AIO system, even the triple fan ones.
I'm probably not communicating this terribly well, I went down this rabbit hole when I was watercooling my old GPU and CPU in a custom loop by EK, I ended up discovering that if I wanted to do sustained work (which I did) then a direct airflow system would have worked better, so I ripped out the loop and it did work better for sustained loads.
If it throttles after 10 minutes instead of after 20 seconds, that is in fact better cooling. The higher thermal mass is one of the major benefits of water cooling over air cooling for this reason.
The air did a better job because it was open. So you average initial temp was higher but could be sustained, because you always had cool air.
If you had a radiator with a fan it’s like the water solution would have still worked better.
2x 240mm rads
1x pump
1x 80mm reservoir
the gpu was a AMD firepro K2000 (not a epic GPU by any standards)
the cpu was a i7-4930k, which is pretty paltry by todays cooling standards.
I think the best setup would be ice cylinders. You put 3-4 packs of ice cylinders that hold good amount of ice in the fridge. Then you plug them into your watercooling loop to cool the water. Probably someone is working (or did work) on a setup like that.
What are people even doing on these newest CPUs? Video rendering? Servers? Because if they are playing games it is a huge waste of power.
All that said, DaVinci Resolve which is increasingly taking over from Premiere for many commercial editors, is more GPU than CPU bound. Lots of sales of the current fastest GPU Nvidia's RTX 4090 to this market.
The energy used for such activities is another question.
If I see 90%+ CPU load (being "efficient"), I need a bigger CPU.
If I hardly see any CPU load, I am being effective.
Ergo, the biggest CPU I can afford is the best choice.
I don't consider unused CPU power as waste, I see it as relief from worrying about capping out.
Edit: I accept your findings, and will pay closer attention to see if I can see the same.
These have been 7th gen and higher i5/i7 machines and newer J4xxx series celerons.
Haven’t had any AMD kit to compare though.
Let me put it a different way: If I'm playing a game and I'm barely using 20~40% CPU, I'm doing good. That 60~80% unused CPU processing headroom is my ability to be worryfree about capping out.
Which is to say: Yes, my 12700K is massive bloody overkill for my day to day activities, but it is 300% adequate for my needs and concerns and I love it. I'll probably upgrade it to a 13700K or 13900K(S) depending on the price a year or two down, since my mobo can accept it (thanks Intel!).
A last-gen i5 mobile processor outperforms at 9600k with a 45W TDP.
People make a ton of noise about the efficiency of processors that are explicitly designed to be the hotrods of desktop computing: meanwhile we've also seen the bottom end get significantly faster over the years. Conversely, the floor for TDPs have barely risen.
so... don't get a top end model or undervolt/underclock it if you care that much?
I don't get all the weird complaining about /halo products/ and /highest end models/ potentially using a lot of power and producing a lot of heat.
It's like, OK? and?