The goal of sync technologies is to prevent tearing from occurring, tearing does not give good visual when in gaming and can’t be distracting for competitive gaming.
V-sync (Vertical Synchronization), enabling it would yield you smooth gameplay experience, preventing tearing from occurring. The concern here is responsiveness of the game (input lag, eg time of click on the mouse and gun fire appear in game) and your GPU have to consistently lock into the frame rates which is the same refresh rate of your monitor.
The problem is lower end graphic card may not be powerful enough or in-game graphics is too high. Your graphic card (GPU) may not produce the frame rates easily to match your monitor frame rate. Example, you want to lock you frame rates at 144FPS based on a 144Hz monitor but due to the graphics card or in-game settings the V-Sync would choose 60fps (lower frame rate) instead of 144FPS as that is less stressful and easier for the graphic card to managed. To ensure each frames is delivered consistently to prevent tearing. In short, the GPU frame rates have to match monitor refresh or it will halved itself.
This is where balance of graphic card and in-game settings plays a role. If your GPU can produce higher frame rates than you monitor refresh rate, V-Sync is a better choice. Where you can lock into the desired frame rates, this is achievable with mid to high end graphics cards. Again, there will be some input lag.
Nvidia’s G-sync and AMD’s FreeSync (variable display refresh rates) works differently from V-Sync. If your GPU may not be powerful enough to match your monitor refresh rate, AMD’s and Nvidia’s solution is to change the refresh rate of the monitor to match you GPU’s frame rates (a total opposite method of V-Sync). In layman terms, if you GPU produce 61FPS you monitor will match it at 61Hz, if it goes higher say 83FPS then the monitor would match it at 83Hz. This would work if you GPU produce frame rates below the refresh rate of the monitor say 144Hz (it can still do 144Hz if your graphics card is capable). Downside to this technology is you have to match your GPU with the Monitor support, RED with RED (AMD), Green with Green (Nvidia), two can’t mix together. Benefit to this is you input lag is much lesser than V-Sync.
Next is cost fact of the monitor, since Nvidia’s G-sync using proprietary hardware in the G-sync monitor it can be costly due to royalty charge to monitor manufactures compare the FreeSync which is open for any monitor manufacturer to use it for free as long it meets the FreeSync standards.
Another solution is Nvidia’s Fast Sync which is a balance between V-sync & G-Sync/FreeSync which can be use on any type of monitor. This is based on Nvidia’s GPU and software to have this function. It works similar into V-Sync off with no tearing, this is achievable if the GPU frame rates is higher than the monitor refresh rate, additional frames readily pushed to the monitor thanks to additional buffer in the GPU. There is less input lag compared to V-sync but still it can’t beat G-sync/FreeSync input lag.
TN vs VA vs IPS | Monitor Panel Comparison:
AOC U2879VF: https://youtu.be/5FlokYV2mak
AOC G2460PG: https://youtu.be/GXHyYkn-2BY
AOC AG322FCX: https://youtu.be/W60SLHlmJmc
AOC C3583FQ: https://youtu.be/PlYfG3wdmDE
AOC I2781FH: https://youtu.be/YXT7Tmc5mhM
Monitor Featured in the video: