FOUND CAUSE Why "System" [ntoskrnl.exe] process always eats 30% CPU

In a previous post "System" using high CPU usage apparently linked to NVIDIA card" I then concluded as I had an apparent success by reinstalling/downgraded to an older 4xx.xx driver, that like others thought it's a problem with the NVidia drivers. Subsequently I then later flagged the post as SOLVED.

This is false as it turned out within a week problem came back! Constant 15 to 20% "system" GPU usage!

I found the cause what the probable cause is for "System" process always eats 30% CPU
In my case it clearly and reproducible lies in an absurdly apparent insignificant area!

I also solved another problem that had perplexed me: for a long time 75% and climbing more of my 32 GB RAM had been used and I never really could find what and why as it always showed there's a allocated and locked private and session process. from time to time my AutoRAM clear app flushed out on average 1 GB.
I downsized my "usual suspects", the caching software [Primocache], cursed at the bloatware windows and other apps that have a sizable memory hunger. but whatever I tried to downsize and minimize little effect if any. All to no avail.

Back to the high "system" usage.
There are so many Q&A on the web about it and some going back five years or more, almost all misleading, cloaked sales attempts, irrelevant or plain wrong. The usual absurd "put the gear on the horse by starting from the back" approach typically ending with"reformat and reinstall" i.e. Windows 10 recommendations.
Never mind the typical conclusion from all the "your time wasting experts" out there that have no clue and just throw around and see what sticks... Do a search "system using 30% CPU" and you get a gazillion returns with that subject, but none of them relevant or plain misleading to say the least. In other words "reinstall Windows": if on your house the front door is jammed you don't tear down and rebuild the house to fix it!

As mentioned in my previous post, I had installed an older version driver NVidia 546.65 as the problem became noticeable with the 55x.xx versions. That worked for about a few days and then the problem was back!
Did some further online "time wasting research" and came across an article with the exact subject title that I had used. Aha! I thought. There the author concluded that after he downgraded to 477.16 drivers, the issue was gone.
So I did that.
That to work for about a day then the problem was back together with Windows update deciding to update my Nvidia drivers with some 36x.xx antiquity since I'm having "old and outdated"ones... thereafter it kind of worked but within 24 hours the problem started to creep up again.

Since my browser shows visited web link text in a a different color, I soon gave up frustratingly as I realized I've been to over hundred different articles...

I did a full VirusScan, but other than some harmless PUPs and "potentially unwanted" there was nothing that could have done any harm. Just some overeager overprotective AV hysterical cry.

I ran tests with various process monitors, process explorers and Windows Performance Analyzer but all to no avail. "System" [NT OSKRNL.EXE] PID 4 hogged there with 15 to 20% constantly.

After a reboot I started up in safe mode but had also disabled any tray applets. I immediately noticed the problem not being present!
There was virtually no % usage of "system".

So I started reboots with selective one by one enabled services and startup apps. But that was way too cumbersome and time-consuming.
I started the system up normally and came across an even worse problem that now my system was gobbling up around 30% continuously. WTF!?

OK, you "don't put the gear on a horse starting from the back unless you want a pair hooves in your face". so I started the reverse approach by shutting down one by one services allowed on the "normal" started and running system. Nothing.

Then I started one by one to shut down all the little [tray] applets all while watching task manager. Nothing much happened and the load was an average 30% on the next click shutting down a tray app icon it suddenly dropped to 15%! Okay, hooray! So turning that on again has to have the reverse effect. It did!I was up to 30% again. shutting down a few more shortly thereafter I got my better than before idle mode percentage back around 6 to 8%!

What I found is that there are [plenty] apps out there that are poorly written and do strange things that are hard to resolve.
The two main culprits were a sound enhancing applet "DFX" And a radio station applet "Tray FM".

While DFX works well in enhancing [pass-through] sound, it does two strange things I have never noticed:
It locks about 6-8 GB RAM gradually increasing [leak?], as private and session process. This drives up the "system" CPU usage by around 10%.
The other one which I will contact the author, is a small free tray applet "Tray FM" which has a small pop-up menu for several genres which you just click on your choice and the selected stations tarts playing. this little f***** tray app gobbled almost 12 GB (!!!) also gradually increasing and cranked up the constant "system" "GPU1-copy" to over 30%! All for nothing!
My automatic RAM clear/flush app popped up more and more often.

Long story short, if you have this high system CPU usage issue, start your system normally and then "unload", eliminate step-by-step each service and tray app while i.e. monitoring task manager activity.

As I wrote this sermon here, hopefully a little bit for your entertainment as well as enlightenment, I have obviously the web browser open, but also a movie running, using Nuance Dragon to dictate all this text, a few other apps open and running and my task manager shows averages between 7 and 13% CPU usage! Latest NVidia drivers: 552.22.
All running 25° C CPU with less than 1.2% GPU usage @ 23° C, all RAM 27% memory load!

PROBLEM [REALLY] SOLVED!

Great- probably a lesson there- start with the 3rd party items - perhaps the less well-known ones?