It could be the screensaver but Windows reinstallation fixed the issue as well :D:D
I had to do it anyway, to restore original MBR ( I had had Linux and Windows installed on one machine )

Changed to normal ( recommended ) power plan - same issue. I run on an admin account.

I use Windows Defender. I hope it's enough to protect my desktop :p Oh and it's independent of my monitor. Same issue occured when I used LG 23MP68VQ-P and ASUS VG245H. Both are with freesync though...

My problem is when I'm AFK for around one minute, the computer goes into some kind of sleep mode ( although I have it disabled in power options and set screen-switch-off-after option to 30 min, and...