1800p isn't scaling to fullscreen on 4k monitor

[The Derp]

So for gaming purposes (Witcher 3 specifically) I discovered that if I added 3200x1800 (16:9 aspect ratio) as a custom resolution in the Nvidia control panel I could achieve my desired framerate.

The problem, though, is that there is a black border around the screen when I switch to 3200x1800 (both on the desktop and in-game), which I'm assuming is due to it not scaling to fullscreen. So then I went into the Nvidia Control Panel went to "Adjust desktop size and position" to adjust the scaling. I changed the scaling mode from "No scaling" to "Aspect ratio" (I also tried "Full-screen"), set it to perform scaling on "Display" (also tried "GPU") and checked the "Override the scaling mode set by games and programs" box. After hitting apply some weird pixelated flickering happens, then it's still the same (so there's still the border), then the pixelated flickering happens again and and it reverts the scaling back to "No scaling", unchecks the "Override the scaling mode set by games and programs" and sets perform scaling on "Display" (so basically it doesn't like it).

It seems to not like scaling up to fullscreen from lower custom resolutions on my 4k monitor. I'm not sure what else there is to try, but any help would be really appreciated.

 

[i7Baby]

Post your build including monitor and OS.

What if you l;eave it at 4K and just decrease settings eg get rid of AA

 

[The Derp]

Post your build including monitor and OS.

What if you l;eave it at 4K and just decrease settings eg get rid of AA

I can run the game at 4k 30 fps with HairWorks, shadows medium, foliage distance high, AA off, and no AO. I'm fine with all of that except for AO being off. I really want HBAO+ on because it makes a huge difference. At 1800p, however, it never dips below 30 with HBAO+ on, but the big border around the screen is frustrating.

Monitor: Samsung U28D590D
GPU: 780 Ti
OS: Windows 8.1 64-bit

 

[i7Baby]

Perhaps you should've bought a 1440p monitor with just one 780Ti. VRAM usage OK?

 

[The Derp]

Perhaps you should've bought a 1440p monitor with just one 780Ti. VRAM usage OK?

VRAM usage is fine depending on the game, for example GTA 5 uses more than 3GB at max settings 4k so I decided not to do it (but I can do 4k 30 fps in GTA 5 very easily), but Witcher 3 uses less than 3GB at 4k (VRAM usage was like 80-90%).


Also, I've solved the issue! For anyone else who experiences this problem (I doubt there are any of you since my problem is rare has hell), download CRU by ToastyX and use that to apply custom resolutions instead http://www.monitortests.com/forum/Thread-Custom-Resolution-Utility-CRU