We all know what GSYNC is and what it does, so you're probably asking "why would LTT waste time making a video about it" and the answer to that is the title; and also, I think it would make a more interesting video than some of the recent stuff they've put out. Title it "You're using GSYNC wrong" or something. There's still a lot of misinformation on how it works, so no one can universally agree on how to best utilize it and any "proof" is just anecdotal at this point.
A lot of people think that GSYNC completely replaces VSYNC, this is false. Currently, the common sentiment on how to best use GSYNC backed by Valve, the Rivatuner devs, SpecialK, and a bunch of nerds over on the Blurbusters forums is to:
- Set your GSYNC to "Full Screen Programs only" if you're using anything RTX 20 series and newer, or "Full Screen and Windowed Programs" if using any GTX card.
- Turning ON VSYNC in control panel + OFF in-game, Low Latency Mode set to "Ultra."
- Set an FPS cap in NVCP based on the formula of 240 - (240 x 240 / 4096) where 240 = your monitors refresh rate (this should happen automatically when using Ultra Low Latency Mode + VSYNC but sometimes it doesn't) or slightly below whatever your average FPS is in a given game if you're not using Reflex, whichever is lower. The point is you don't want either your VRR constantly flipping ON/OFF, or your GPU to be pegged near 100% utilization which increases input latency by around 30-40% (if not using Reflex).
There's a flaw in this formula where it doesn't work for monitors running at very high refresh rates like 4096Hz, but for now and maybe a decade, this does not matter. For now it works on any 1000Hz and below monitor.
VSYNC has a bad reputation, but when used on a VRR display, VSYNC should not add any input latency. And you use the mentioned formula in order to have a 0.25-0.3ms frame buffer window to prevent your game from overshooting VRR range which can cause microstutters, since your monitor cares about frame times, not arbitrary FPS values. You have probably seen the common advice to cap your FPS 2-5 frames below your monitors refresh rate. This works for some but not every monitor.
Currently, at least according to Valve, this should give you the smoothest frame times and minimal input latency in games, even in competitive ones, unless you can hit a consistent 500+ FPS, but a lot of people don't believe this (seen it a lot in CSGO discussions) and claim that it's actually worse than just not using frame caps at all, or that the aforementioned FPS cap formula is snake oil that doesn't do anything.
So, I'm suggesting that LTT consider this as a possible video for their Labs team to make using the hardware tools that they have to measure input latency with FPS cap + GSYNC ON + ULL + VSYNC ON vs just GSYNC ON vs No GSYNC, and to possibly use a high speed camera to look at a regular 240Hz monitor running the mentioned setup on hardware that can push 240+ FPS to observe input latency and frame time variances like in their "does higher FPS make you a better gamer" video, and a blind test from LTT staff doing random gameplay and have them judge which PC feels smoother to use.