All credits to this dude: jim2point0
DSR (Dynamic Super Resolution)
is downsampling method for Nvidia GPUs. It provides better Anti Aliased picture with sharper textures due to increased resolution. It's technically better than ordinary Custom resolutions since the blur filter it uses; helps eliminate the jaggies (The default 33% filter looks bit too blurry on my monitor, but 22% gives a sharper+smooth pucture)
With DSR you can't set custom resolutions which is really a let down. You can only have multiples of your native resolution. That also means, you cant have different aspect ratios.
But with the method shown in the above link, you can have any resolution. Just keep in mind that, do not try to Upscale/Upsample. You can only downsample, tryi g to Upsample will cause further terrific problems (Mentioned in page 2 of that link)
For a native res of 1440x900, you can't use any DSR resolution of width and height below 1440x900 respectively.
Oh, use it on your own risk. But so far, no problem occured to me as long as I not tried to upscale.