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Gsync ON or OFF when FPS always matches refresh rate?

Posted: 31 Jul 2020, 01:13
by r3lik
Hello all,

Long time lurker, finally signed up.

As the question states in the subject, should Gsync be ON or OFF when FPS==monitor refresh rate? To my understanding, there is no benefit to having Gsync on in that scenario, and it could be better to use ULMB in that case.
Is there an input lag penalty for having Gsync enabled when there is no need for it in terms of variable refresh rate?

Thanks!

Re: Gsync ON or OFF when FPS always matches refresh rate?

Posted: 31 Jul 2020, 01:26
by Chief Blur Buster
r3lik wrote:
31 Jul 2020, 01:13
Hello all,

Long time lurker, finally signed up.

As the question states in the subject, should Gsync be ON or OFF when FPS==monitor refresh rate? To my understanding, there is no benefit to having Gsync on in that scenario, and it could be better to use ULMB in that case.
Is there an input lag penalty for having Gsync enabled when there is no need for it in terms of variable refresh rate?

Thanks!
Yes & No -- depends on your goals.

If you're trying to avoid VSYNC OFF, then framerate-capped G-SYNC has lower input lag than ordinary VSYNC ON. For example, if you have a 165Hz monitor, use an approx 162fps cap to have very easy low-latency VSYNC that's not fiddly, and will be forgiving during frame rate dips.

However, if you're playing competitively, then framerates massively beyond refreshrate, during VSYNC OFF, can produce lower latency, due to the way ultra-high VSYNC OFF framerates literally streams multiple frameslices per refresh cycle in real time during scanout. Screens refresh from top to bottom (www.blurbusters.com/scanout) and VSYNC OFF can essentially splice new frames mid-scanout, without waiting for the next refresh cycle to begin. However, there are side effects such as tearing and/or microstutters. For this reason, CS:GO gamers often play using VSYNC OFF. However, with upcoming 360Hz monitors, the opportunity arises to have a framerate range completely within VRR range, in a larger selection of games, and the ultra-fast 1/360sec scanout, makes VSYNC OFF less necessary.

Re: Gsync ON or OFF when FPS always matches refresh rate?

Posted: 31 Jul 2020, 01:53
by r3lik
Thanks, I will continue to keep using GSYNC ON, VSYNC ON + Frame-rate cap.
Love the site!

Re: Gsync ON or OFF when FPS always matches refresh rate?

Posted: 31 Jul 2020, 13:47
by r3lik
If you constantly push 139 fps and cap frames does it still make sense to use gsync on, vsync on in that scenario. There is no VRR here, right since you're always at 139 fps?

Re: Gsync ON or OFF when FPS always matches refresh rate?

Posted: 31 Jul 2020, 14:05
by jorimt
r3lik wrote:
31 Jul 2020, 13:47
If you constantly push 139 fps and cap frames does it still make sense to use gsync on, vsync on in that scenario. There is no VRR here, right since you're always at 139 fps?
VRR is still fully active at 139 FPS 144+ Hz.

You don't need a constantly fluctuating framerate to benefit from VRR, as it's still matching the display rate to the render rate so long as the FPS is within the refresh rate, which equals no sync-induced input lag or sync-induced stutter, and no tearing.

There's really no situation where it's better to use standalone V-SYNC if fully featured VRR is available to you. The only real exception is if you're strobing and need tear-free FPS = Hz, at which point you can't use VRR anyway (unless you have a ELMB-Sync-capable display).

Re: Gsync ON or OFF when FPS always matches refresh rate?

Posted: 31 Jul 2020, 14:07
by r3lik
Thanks, that makes more sense.