How to explain the lack of sharpness in games when rotating the camera and aiming?

Question

Iron

Good day, the question may sound very incomprehensible, but I can’t describe it in another way. The fact is that about a couple of years ago, one day, once again playing Overwatch, this problem began. It just came out of nowhere and that's it.
The essence of the problem: when playing any online and not only games, one feels not full responsiveness in control, a la a game with input lag (it feels like vertical synchronization is on and the cursor moves slowly), but in shooters of the same this parameter is decisive, so there is no question of any playability.
Here's what I did: I bought a whole new PC parts, a new monitor, keyboard and mouse. I reinstalled Windows of different versions, played with nvidia software and settings in Windows, settings in the game itself. I wore my PC to a friend's apartment - everything is super there, just like I once had. A friend brought his PC to my house - the same garbage as mine)
I have been suffering with this issue and problem for 2 years now. Do not ask anyone - they think that the troubles are with the head, but, alas, this is not so.
I tried to google many times, I also wrote on the forums, but no one came across this. I found a couple of discussions on YouTube under the video, but no one solved anything there either. What to do is unknown. And spent a lot of money on PC.
My characteristics on the current PC:
Ryzen 5 3600 (I don’t play with overclocking)
MSI B450-A PRO MAX
MSI GTX 1060 6gb OC
Kingston HyperX Fury Black 16gb(8x2) 3200 MHz
BeQuiet! Pure Power 11 600w
SSD Crucial BX-500 960gb
Monique Samsung C27F390F
Last PC was:
i5-4690k
Gigabyte GA-H81M-DS2
Kingston ddr3 8gb(4x2) 1333 MHz
Gigabyte gtx 960 4gb windforce oc
Xigmatek 500w
HDD Toshiba 1tb
Monique ancient from LG (I don’t remember the model)
PS The only answer to this problem that came to mind after everything that I did was problems with the wiring / network in the house / apartment, but because In these matters, I am a complete amateur, I don’t even know where to start.

Answer 1

Check mains voltage.
Ping the network for stability.
Try connecting to the internet directly, without a router.