First things first

What you need

What is downsampling

Why

How

-ATTENTION-

Performance

Issues

Screenshots

Do this at your own risk, I've dabbled in downsampling for almost two years and I've never seen, read or heard anyone have "anything break" by using downsampling. Worst thing that has happened to me while doing it has been a freeze or two during the process. Hopefully it's easy enough to follow andwork for people with modern nvidia gpus and monitors. If it does feel free to share the settings that worked ( or those that didn't work for that matter ) along with your own setup. I won't take any responsibility for the tiny chance of your pc coming to life and strangling you while you sleep poltergeist style.An Nvidia GPU ( use this for downsampling on AMD cards ) , Windows 7 ( SOME people have issues with this method on Windows 8 ) and 10 minutes worth of patience. From my own experience going from 4xx to 5xx and 6xx series the downsampling compatibility has become better. Everything written here has been tested and has worked for me on the following setup :Dell u2312hm 1920x1080@60 hz monitor -> Single link DVI-D to HDMI -> Gigabyte GTX 670, 310.64 Gefore Drivers. Downsampling can be very finicky across different driver versions but apparently any recent set of Geforce drivers should be compatible, version 300.xx and newer.Downsampling, also called OGSSAA : Ordered Grid SuperSampling AntiAliasing, is in this case the concept of rendering the game at a much higher, custom made, resolution than your monitor is capable of displaying and subsequently having the GPU rescale the image ( as in downsample ) to that of your monitor's native resolution to which the end result is a "cleaner", sharper and less aliased image.King of all AA methods, affects virtually every kind of aliasing but it's also very taxing which is why we have other less demanding alternatives, SMAA, MLAA, FXAA etc. Sadly we are in a position where we have pc-games shipping with "AA on/off" options or have AA implementations that leads much to be desired making people use other forms of externally forced AA.We're also at a point in this "generation" where the discrepancy between pc and console hardware is bigger than ever giving pc-users a much larger performance overhead. What I mean by that is that there are a lot of people out there with hardware that can run many/most new games and virtually any older game at higher resolutions than 1920x1080 while still maintaining an acceptable framerate even though 1920x1080 is still the standard resolution of most of our monitors.Using downsampling you almost never will have to worry about a game's image quality being ruined by lack of AA since it works in almost any 3D game out there. Compared to other types of AA solutions like SMAA/FXAA-injectors or "Nvidia Inspector AA" you won't need to fiddle with settings or files at all, when it comes to downsampling via custom resolution once you got it up and running it's just a matter of using that resolution in any game and presto you got yourself some AA brewing. It is worth pointing at that downsampling still works great with those aforementioned AA methods ( injectors, inspector etc ) and whatever kind of AA solution/s the games you want to play offer, you can mix,match and stack AA to your heart's content.There are guides out there that go much more in depth in the process, one of them is this thread/guide at Guru3D showing the step by step guide on how to reach your own maximum custom resolution. The problem is that following those guides myself I've noticed that the end result is almost random at times, giving me different max resolution depending on things like drivers rather than which settings I ended up using. In the end, the best method I've found is to simply straight up copy other people's settings ( this is by no means a guarantee that it'll work but hopefully it removes a lot of the hassles of trying to stumble across your own max resolution one pixel at a time ) and hope for the best.If the above two resolutions won't work at 60 Hz try 59 Hz.OK. Following the different guides that exist out there, my own max resolution was 3200x1800 for a long stretch of time. That was until I started copying other people's settings which showed me how arbitrary the results could be. Using person A's settings didn't work but somehow using person B's which used an even higher resolution did without changing anything other than the resolution. But you want an even higher resolution so let's see what we can reach!What kind of performance to expect?speaking your performance will be 1/N, where N is supersample value or "how many times more pixels you're rendering".Example : When downsampling from 3840x2160 to 1920x1080, which is technically 4XSSAA, you're rendering 4 times as many pixels at 3840x2160 as you are at 1920x1080, so you'll be getting 1/4th performace. E.g, if you have 120 fps at 1920x1080 you'll get 30 fps at 3840x2160 in game X ( barring vram limitations, other bottle necks and everything in between ).Doesn't appear to be working with laptops and/or "m" line laptop gpus.Reinstalling drivers clears your custom resolutions so have your own settings written down/saved somewhere.For some people using refresh rates that aren't 30 Hz or 60 Hz exact, the custom resolution won't show up ingame OR selecting the resolution in game will make it crash.Bandwidth issues - Depending on the way you've hooked up your monitor/gpu you have different maximum bandwidth that can come into play. Interestingly enough, using my monitors dvi output with a single-link DVI cable gave me better results compared to using the displayport ouput which has a higher bandwidth.Depending on your general preferences you might notice an increase in input lag as you downsample from a higher resolution. Some people claim they don't notice any kind of increase in inputlag whereas me and my irl buddy and fellow gaffer Tyrantguardian ( both fighting game nerds ) experience a noticeable increase in inputlag in certain games where such a thing is easily noticed.You can't downsample in games where you use windowed mode unless your desktop is set to the high resolution you want to downsample FROM.120 Hz and 3D-gaming : due to current bandwidth limitations it isn't feasible to downsample down to a 1920x1080 resolution @ 120 Hz.I won't bother with posting a sea of screenshots, for that I'll redirect you to the 2013 High-Res PC Screenshot Thread where you can see how good games can look when using downsampling. I will however post a couple of cropped comparison pics from Dota 2. It's no technical showcase game by any means BUT I do think one thing comes across and that is the visual difference between downsampling andrunning the game at max settings. This can be quite striking considering you already had the game running at what you thought was the highest visual fidelity.these aren't meant toanyone but you will notice that everything that is dependent on resolution will look tangibly better ( certain lighting effects, texture detail, shadow detail, model detail and of course a sharper, less blurry, less aliased image ).Images are details cropped and resized x2 from a)1920x1080 and b)1920x1080 downsampled from 3680x2070. Open in separate tabs and flip side by side to see the difference in Dota 2 a game that lack AA options. ( Keep in mind that these are upscaled, here's an example of what it looks like ingame with hud turned off. Bonus Dirt 3 comparison.And for the hell of it, here's some Mirror's Edge using downsampling and ingame AA.