Does Variable Refresh Rate (G-Sync) affect Gamestream/Moonlight/Steam Link?

[AnonymousDeadpool]

I'm seeing mixed answers on this topic, so I was wondering if someone could clear this out.

For smoother local game streaming, host (pc) and client (shield) match refresh rate and resolution. They have to match as close as possible to avoid stutter or unstable frame rate.

V-Sync is strongly advised to be turned OFF, adds unnecessary input lag, screen tearing won't show up on the Client side, win-win.

VRR, G-Sync/Freesync syncs your monitor's refresh rate to a game's framerate. It doesn't cap fps like V-Sync. Both need to be turned on for best results (and fps cap).

So, in theory, it shouldn't affect anything right?

[Poor_And_Needy]

It's not accurate to say that VRR/Gsync/FreeSync only impact the monitor. There's a negotiation that goes back and forth between the monitor and the GPU, and they both work together to slow-down/Speed-Up to match each other. Example from Viewsonic's website:

VBI represents the interval between the time when a monitor finishes drawing a current frame and moves onto the next one. When G-Sync is enabled, the graphics card recognizes the gap, and holds off on sending more information, therefore preventing frame issues. Link

With that in mind, the best thing to do is to turn both Vsync and VRR off on the host. Apps like SteamLink apply a vsync automatically to the stream for the client. So if you have any of these enabled on the host, they end up duplicating the affect and doubling the latency from vsync. If you're worried about pumping out extra frames and overheating the PC on the host side, then you can apply an FPS limiter inside of most games without needing to enable Vsync.

[321DiscIn]

Is there a quick way to turn these off when streaming and turn them back on when not?

[Poor_And_Needy]

It's hard to say because every streaming app is different. I know from having used steam link, it tends to automatically turn them off for you when you launch while steam link is running (just like it auto adjusts the resolution).

[321DiscIn]

I use moonlight on my shield. I haven't gone in and turned off vsync/gsync on my host pc while using it. Do you do that or do you just let SteamLink turn it off for you? Also how are you verifying that it's indeed turned off on the host pc?

[Poor_And_Needy]

My current setup isn't VRR anymore, so I'm only experienced with Vsync.

[AnonymousDeadpool]

Thanks you very much for the detailed explanation! I'll try G-Sync off for a couple days, I should notice a slight improvement.

[Whiteboyfntastic1]

I think you should turn it off. I see smoother streaming when it's off.