Quick overview
- Async (default) – Good for most games, gives stable frame pacing.
- Front/Back Edge Sync – For smoother timing or fine-tuning screen tearing.
- NVIDIA Reflex – Lowest input lag, best for competitive games (NVIDIA GPU only).
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RTSS has a few different frame limiter modes. They sound kind of technical, but picking the right one can help your games run smoother or feel more responsive. Here is a simple look at what each mode does and when you might want to try them.
Async mode is the default
This is the standard mode most people use. It keeps one frame buffered to help keep frame pacing smooth. It works well for most games, especially if you are not chasing super low input lag.
It helps reduce stutter and gives pretty stable frame times. But since it buffers one frame, it can add a bit of input lag. That might be a problem for games that need quick reactions.
Front Edge Sync starts at the beginning of the refresh
This one syncs the frame to the start of the screen's refresh cycle. It can make animations look smoother and keep frame timing tighter. Some people use this with Scanline Sync to help with screen tearing.
It is a good choice for games where timing matters, like rhythm or simulation games. But it might take a few tries to get it working just right.
Back Edge Sync starts at the end instead
This works like Front Edge Sync but at the other end of the refresh cycle. Some people prefer it when trying to shift the tearline using Scanline Sync.
If Front Edge Sync does not give the result you want, this is worth trying. It is also a bit advanced, so it might need some testing to get it right.
NVIDIA Reflex mode reduces latency
This adds NVIDIA Reflex to RTSS. It helps cut down system latency by shrinking the render queue. That means less delay between your input and what shows up on screen.
Use this if you play competitive games and want the lowest possible input lag. It is also useful if a game does not support Reflex by itself. Just make sure your GPU supports it first. If the game already has Reflex built-in, use the in-game setting instead.
Which one should you try?
If you just want smooth gameplay without messing with settings, Async is fine. For better frame pacing, try Front or Back Edge Sync. And if you want the lowest input lag possible, go with NVIDIA Reflex mode.
It is best to test a bit and see what feels right for your setup. Different games and monitors behave differently so one mode might work better than the others depending on what you are playing.
Sources: Blur Busters Forums, Guru3D Forums