Things you need:
- A 120hz monitor. (VG248QE can be run in 120hz no problem)
- A game with in-game framerate limiting console commands (preferred) or a framerate limiting utility(msi Afterburner, Nvidia Inspector, etc...)
- The ability to run your preferred game above 70 fps for the whole duration of the demo.
You will want to load up the game with vsync and triple buffering forced on. Ensure that your refresh rate is at 120hz and are putting out at least 70 fps constantly in the place where you’re going to perform the demo.
Now, open the console and limit your fps to 60. (press tilde (~) and type in the console command to limit the fps)
Smoothly pan the camera left and right and observe how smooth the motion is. This is perfect 1:2 harmonics. This is as good as 60 fps can possibly look and feel. Every single frame is displayed on the monitor for the same amount of time. There is 1 frame for every 2 refreshes.
Now, try bumping the fps limit up to 67 and smoothly pan the camera left and right some more. Pay particular attention to dark trees against bright sky, or dark doorways on bright buildings. You will notice at certain panning speeds that DESPITE THE HIGHER FPS, your turning speed will appear to “shudder” a little bit and be less smooth than 60. This is caused by the fact that there isn’t a set number of refreshes for each frame.
In order to fit in 67 frames into 120 refreshes, most of the frames will take 2 refreshes, but some will take 1. In each frame you are panning the same amount, but some are only displayed for half as long as the others. This will lead to the jerky movement. This is what Gsync fixes. Rendering 67 fps? You have to fit it into 67 refreshes. It will be perfectly smooth.
A little more on harmonics...
There are more harmonic framerates where the motion will smooth out perfectly than just 60@ 120hz. The easiest way to find them would be to divide the refresh rate by an integer. (120/2)=60 fps for perfect 1:2 motion. (120/3)=40 fps for perfect 1:3 motion, etc.
I run my monitor at 144hz, therefore my harmonic framerates are 72, 48, 36, 24… so on and so forth. Because 72 fps is a harmonic framerate, it is smoother than 80 fps. If a game is hardware intensive and spends most of its time below ~110 fps, I’ll limit the framerate to 72 to preserve as much motion fluidity as I can. If you have a VG248QE and play a particular game between 60-90 fps, I'd recommend limiting your fps to 72 for that game as well.
