Nvidia G-Sync and AMD FreeSync, All you need to know

There are a variety of methods for compensating for the delay between screen updates and gameplay frame rate, ranging from the crude method of capping your game's frame rate to match your monitor's refresh rate to the more sophisticated realm of variable refresh rate.

VRR(Variable Refresh Rate)  allows the two to sync in order to avoid artefacts like tearing (where parts of different screens appear to be mixed together) and stuttering (where the screen updates at perceptibly irregular intervals). Basic in-game frame rate control to pricey hardware-based implementations like Nvidia G-Sync Ultimate and AMD FreeSync Premium are among the efforts.

Which VRR system to choose depends on which graphics card you have (especially now that you can't really buy a new GPU) and which games you play, as well as the monitor specs and options available. FreeSync Premium and Pro, as well as G-Sync and G-Sync Ultimate, are mutually exclusive; you'll rarely (if ever) see monitors with both options. In other words, the VRR scheme you get is largely determined by your other choices.

Which VRR system to look for when choosing a monitor is determined by your graphics card (especially now that you can't really buy a new GPU) and the games you play, as well as the monitor specs and options available. FreeSync Premium and Pro, as well as G-Sync and G-Sync Ultimate, are mutually exclusive; you'll rarely (if ever) see monitors with both. In other words, your choice of VRR scheme is largely determined by your other choices.

G-Sync Compatible and FreeSync

Improved versions of an adaptive refresh, branded G-Sync Compatible and FreeSync, are found in the bottom tier of Nvidia and AMD's VRR technologies. They improve VRR performance by using GPU hardware, but they're hardware technologies that are common to both Nvidia and AMD GPUs, so you can use either if the monitor supports it, as long as one manufacturer's graphics card driver allows you to enable it for the other manufacturer's cards. G-Sync Compatible, unlike FreeSync, implies that Nvidia has tested the monitor for an "approved" level of artefact reduction.

G-Sync and FreeSync Premium

G-Sync and FreeSync Premium are the first serious hardware-based adaptive refresh levels. They both require monitor-specific hardware that works in tandem with their respective GPUs to apply more advanced algorithms, such as AMD's low-frame rate compensation and Nvidia's variable overdrive, to achieve better results with less performance overhead. They also have baselines for monitor specifications that meet the required standards. However, because G-Sync uses DisplayPort's Adaptive Sync, it still only works with DisplayPort monitors, which is frustrating because it does work with HDMI TVs.

G-Sync Ultimate and FreeSync Premium Pro

G-Sync Ultimate and FreeSync Premium Pro are the top VRR technologies. Both require a full ecosystem of support, including the game and monitor in addition to the GPU, and primarily add HDR optimization as well as additional VRR-based compensation algorithms.