So I have a BenQGL2250
It's like 2 or 3 year old, and barely "overheating" next to the buttons on bottom right

My issue is that, the screen changes its resolution to something else than D-Sub, which is my main source.
I can't go hdmi, for some reason that doesn't work
I just for instance had a whole hour and a half of black screen trying to reboot my computer and hopefully get back on the right source, I managed to get into the source menu when it booted, and even though I had D-Sub selected, still had a black screen.
It randomly got back to normal.

I usually happens when my screen goes off mode

I thought it was cause I had 2 screens settings, but it's not
Running through DVI on comp + VGA on screen (DVI isn't supported lul)
Reinstalled all drivers already, did a bunch of tweaks here and there trying to find out the problem.

Oh well.

What the hell? I'm confused. Are you running DVI or VGA?

Try another video source like a TV or hook up another device to ensure its the monitor that's buggy and not something else.

vga barely handles 1280x1024@60hz i imagine 1080p would be pushing it too far
have you tried a higher quality cable

vga on monitor (blue) and dvi (black) in desktop

@dcss i bought this monitor like 2 years back and the monitor i had before was handling it quite perfectly

cable could have degraded over time?
it's VGA

this is 2018
if you using vga
you in the wrong decade