Specs:
Desktop PC, custom build.
MB = ASUS Zenith Extreme X399
CPU = AMD Threadripper 1950X
GPU = AMD Rx Vega 64
32 GB RAM
Monitor = Acer XR341CK via DisplayPort
Windows 10 x64 build 1709.

I have monitor stand by set to 10 minutes.

The monitor stands by, then eventually, even without moving the mouse or touching the keyboard, it will wake by itself, then after a second timeout period it will standby again, this time for good.

To test this more efficiently, I set the monitor standby to 1 minute, and this happens every time (100% reproducible).
- I clocked the issue to 4 minutes i.e. the monitor wakes 4 minutes after the monitor goes on standby when set to standby after 1 minute, meaning 5 minutes after all input stops. Schematized:

Code:
Time = 0, I stop touching keyboard/mouse
Time = 1 minute, monitor stands by
Time = 5 minutes, monitor wakes by itself.
Time = 6 minutes, monitor stands by, and stays put this time
Oddly enough, setting standby to 2 minutes keeps the same time table (only change from above is in red):
Code:
Time = 0, I stop touching keyboard/mouse
Time = 2 minutes, monitor stands by
Time = 5 minutes, monitor wakes by itself.
Time = 6 minutes, monitor stands by, and stays put this time
Now, this mentions it is due to Firefox: https://www.thefreewindows.com/14060...diately-sleep/
However I shutdown Firefox and it still happens.

Anyone has a clue why this would happen?
I don't think this is an issue with my system, because even though I just finally decided to post about it now, it's been doing that for as long as I remember, from when I was still on Windows 7. I've been through Windows 8, Windows 8.1 and Windows 10 since then, and changed motherboard/RAM/CPU 4 times, graphics card 5 or 6 times, and monitors 3 times, and with all those hardware combinations the problem was present.

Seems to me like this is inherent to how Windows manages power? Anyone knows what Windows could be doing after 5 minutes that wakes the monitor?
Or maybe this is an AMD-specific issue? (I only ever had AMD systems).