1 thread is loaded at 100% and the rest work in the usual mode for themselves. PC freezes! AMD Ryzen 5 1600X. What's the matter?

Question

Iron

The computer was assembled 13 months ago.
Mother - B350 TOMAHAWK (MS-7A34) (AM4)
OS - Windows 10 Pro 64-bit
Proc - AMD Ryzen 5 1600X
RAM - 16.0GB 2-channel RAM
Vidyuha - NVIDIA GeForce GTX 970 XtrimeGaming
I have 2 HDDs. The first one is called "E" and there are all sorts of things on it, the second one I divided into 2 discs - "C" and "D".
On "C" is the OS on "D" all good. So, when this problem appeared, I tried to solve it, but everything was in vain and I decided to reinstall Win. I did this by "Reset the computer" with deleting all data from the "C" drive and then formatting it. Disks D and E were not touched (I wanted to fortify all the disks, but there is no portable HDD, and there was nowhere to put any good with D and E).
Did defragmentation with both standard defr and Auslogics Disk Defrag. (Yes, I know, there are solid viruses in it, but right after the defr-ii I deleted everything and cleaned it from viruses.) I
checked with the Dr.Web scanner, removed all viruses and checked again. There are no more.
I scanned for viruses in Nod32 Antivirus, deleted those that I found and they were not there when I rescanned.
I cleaned the registry in CCleaner and cleaned it several times.
I also scanned for unwanted software and files with AdwCleaner 7.2.4.0 and Malwarebytes.
From the moment when this problem did not exist and until it appeared, the system was not subjected to updates or installations of any firewood. It appeared spontaneously.
I came home from the watch, the first day I played and everything was great in GTA and BF. turned off the computer, went to bed. The next day I turn on the computer and understand that something is wrong. Wild friezes appear in video games and fps drops dramatically. Moreover, the fps freezes and drops, both in large games like GTA, and in pixel games that even run on a dandy. Brakes are also noticed during normal use of the PC. Restarting the PC did not help *that day (But sometimes they do. Most often, restarting through shutdown helps.). But the next day the problem disappeared. But the next day it appeared again. It seems to me that the friezes appear absolutely randomly, apparently something starts some kind of process that loads the stream.
Turning off the Internet helped once, then I thought it was some kind of miner virus. I looked at a bunch of information on this topic, checked both in dis.tasks and in TechPowerUp GPU-Z the load on the vidyuhi and the CPU in games and idle time. There was no extra load on the vidyuhu, the temperatures were standard, as well as on the CPU.
Another time, turning off the Internet did not help, and then I decided to turn on the cpu value in the PlayClaw 5 Plus overlay to "show each core" and noticed that every time friezes appear, 1 out of 12 bus is constantly loaded at 90-100% while others work as usual. The CPUID HWMonitor is the same. Moreover, 1 thread is constantly loaded even in idle time under 70%, while others show 0-4% and the first core has more voltage than others.
In the first two screenshots, the PC is at idle, in the next, while playing GTA.
The first screenshots of "1." made when there is a problem and everything slows down. The second "2." done when there is no problem. In the future, I can provide a video, but the picture there is exactly the same as in the screenshots.

Answer 1

The performance tab of the dispatcher, as well as the resource monitor, will tell a lot more about the brakes in dynamics. special attention should be paid to the metrics of the various queues.
I suspect that Windows updates are being installed.

Answer 2

IMHO, it's a driver issue. Download process explorer and see who loads the processor. If these are interrupts, then there is clearly a problem with some kind of driver. Along the way, you can see if this is a process, then in the properties on the treads tab you can see which thread takes CPU time.