Question Fullscreen games run at a lower refresh rate than my monitor

[g76agi]

So a while back i overclocked my BENQ 60Hz monitor to 80Hz, and ive had this problem where some games would still run at 60Hz if played on fullscreen (no vsync, not a performance issue, not capped FPS) For example osu! runs at 80Hz on Fullscreen, but Apex legends does not, i either have to A. Go windowed/windowed fullscreen or B. Lower my resolution and then play fullscreen, i have no idea why this is happening and only for some games aswell, same happens with csgo/valorant, games will run at 60Hz fullscreen but 80Hz borderless/windowed.

I cant find any post online about anyone having this issue so im creating a thread myself.

And just to be clear, apex is locked to 144FPS, it runs at that at both 1920x1080 fullscreen and 1280x1024 fullscreen, yet for some reason runs at a choppy 60Hz at 1920x1080 but a smooth 80 on 1280x1024 (yes its that big of a difference, i actually get motion sickness if i try to play it native res fullscreen)
I have 80Hz selected in both my nvidia control panel and the windows display settings, im using windows 10

My specs are:
CPU: Ryzen 5 3600
GPU: GTX 1660Super
RAM: 16GB DDR4

 

[kerberos_20]

if game doesnt offer in its video setting monitor refresh rate to be changed, then it will default to monitor native value
you could probably run CRU and edit your monitor settings there to have "native" 80Hz, then with edid override you can load it up in your OS (requires editing windows registry)

 

[g76agi]

if game doesnt offer in its video setting monitor refresh rate to be changed, then it will default to monitor native value
you could probably run CRU and edit your monitor settings there to have "native" 80Hz, then with edid override you can load it up in your OS (requires editing windows registry)

But why does lowering the resolution while still being fullscreen then change the refresh rate to 80?

Im honestly not even looking for a solution as much as im just genuinely curious since ive never seen something like this