JackE said:

Also, you said earlier >>>but the fan is running at 1798 rpm>>>Just a normal sound of a fan running at high speed - and the air flow out of the machine is accordingly strong.>>>. How did you measure this rate? 1798rpm should not sound very loud? Jack E/NJ 

 That's what I tried to say in my earlier post: I'm pretty sure that the fan is running faster than the Performance Monitor shows. I have not measured anything, it's just that I remember this machine being very quiet earlier, you could hardly hear the fan running at all when I was not doing anything demanding. And now the fan runs equally loud all the time, regardless of what I'm doing, whether I'm only writing this message on the browser or playing a graphics heavy game - the same fan noise level constantly.

Juha

I think the fan behaviour has been like this right from the beginning with the new board running on the Deltaco. But it was not until I installed the Performance Monitor that I started to realize that the fan noise doesn't correlate in any way with the temperatures or CPU  usage.

I sent a message to Deltaco support the day before yesterday, but haven't received any reply yet.

Juha

But why did you say that you remember this machine being very quiet earlier? Was it perhaps on the original mainboard and original charger?

Yes, that's what I meant.

Was the Deltaco ever used on original failed mainboard? Jack E/NJ 

No, it wasn't.

Fan stuck on high speed and machine freezing or bluescreening under load when using Nvidia graphics. Other than that the machine seems to work OK.
But no, I have not been using the Deltaco since I found that the original charger mysteriously works after all (see my post on August 13). 

I got today a reply from Deltaco: their charger is not able detect anything, it simply puts out the voltage that is determined by the chosen connector. Which means that I did drive this new motherboard with 19 volts when using the Deltaco.

I don't know if it's worth trying to troubleshoot this any further after this info, but here are answers to your questions anyway:

I did already update bios to version 1.15 as part of my update session in which I updated all drivers, bios and windows to the latest versions (see my post on August 20).

For monitoring I've been using Performance Monitor which comes as part of the DriverBooster package, but a couple of days ago I installed also CPUID HWmonitor which gives much more information, like temperatures of individual cores and min/max values for all measurements.
Below is a screenshot of this program, taken after a few hours of machine use, including kids palying some Minecraft and Sbnautica and myself doing some web browsing and other lighter tasks.
There are some momentary core temperature peaks reaching over 70 degrees, but most of the time when I was actively monitoring, all teperatures were between 40 and 60. All this time there was no changes in the sound of the fan.
Nvidia GPU is not shown here as I have it disabled at the moment.




Juha

OK, I enabled Nvidia: when idling, its temperature is about 37-40 degrees. I started Minecraft as a test, and when playing the temp ramped slowly up to 50, and then stayed at about 48-50. Also tried Subnautica, which this time didn't make the whole machine freeze, but didn't get past the loading screen. Also here, when the game was trying to load the temp went up to 50 but not higher.

And again, no change in the fan noise.