Remember when Maxwell chips hit the market and the big selling feature was running the game at a HIGHER resolution than your display then downscaling it to get a higher fidelity gaming experience at your chosen resolution because the cards were just THAT amazing.
I myself was a user of nVidia Dynamic Super Resolution. Back when I had a 1920x1200 display, I used DSR to run games at the 16:10 version of 4K (3840x2400) downsampled to 1200p. Looks waaaaay better than native 1200p. After I moved to 1440p, I ran some games at 5K (5120x2880) downsampled to 1440p via DSR. DSR itself incurs about a 5% performance penalty. I had friends with Radeons who used VSR (Virtual Super Resolution), the AMD version of DSR. I even use downsampling on my PS4 Pro, with 4K being downsampled to 1080p on my HDTV.
The reason I stopped using DSR was mainly because it requires exclusive fullscreen, and as someone with 4 displays connected to my main PC, I usually roll with borderless window mode. Also I wanted to make better use of my high refresh rate display, so I usually opt to keep games at 1440p and try to reach higher framerates instead. It really depends on the game though. Some games have such a light rendering workload (either due to age or because they aren't graphically demanding to begin with) that it makes sense to just run them at a higher res and then downsample. For example in
Halo MCC I can run at 5K and my framerate is still well above 100fps.
If I had a native 4K display then I wouldn't have to use DSR, I would just run games on either the 1440p display or the 4K display, depending on the resolution I wanted for a particular game. That's how some of my friends roll. They have a 1440p monitor and a 4K HDTV hooked up to their PCs, and depending on the game or their mood they just switch between the two.
If you have a really powerful GPU but do not yet have a display capable of bringing out the full potential of that GPU, downsampling is your best bet. Internally the game still renders at the higher resolution, so you aren't wasting the power of the GPU on lower resolutions. The downsampled image looks way the f*ck better than the standard-res image.
