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When running a game at around 120-150fps on a 240hz monitor, is there an input lag difference between GSYNC ON and OFF? Assuming VSYNC is off.

The reason I would assume GSYNC OFF would win is because the monitor stays at 240hz. Anyone know anything?

neverendingstory wrote: ↑

07 Jul 2020, 12:05

When running a game at around 120-150fps on a 240hz monitor, is there an input lag difference between GSYNC ON and OFF? Assuming VSYNC is off.

Depends on whether your priority is:
- Absolute lag
- Latency consistency
- Latency volatility

neverendingstory wrote: ↑

07 Jul 2020, 12:05

The reason I would assume GSYNC OFF would win is because the monitor stays at 240hz. Anyone know anything?

That's not the reason. Remember not all pixels refresh at the same time. The monitor permanently stays at 1/240sec scanout (in high speed scanout videos) at all framerates (refreshrates) in the VRR range. So even 150fps G-SYNC still shows in 1/240sec G-SYNC.

VSYNC OFF, is lower lag for screen middle/bottom because it is scanout-bypassing, allowing new frameslices to be spliced mid-scanout. However, G-SYNC provides much more consistency and less stutters (since stutters can wreck aiming in some games).

Latency is never a single number, because not all pixels refresh at the same time.

So assuming I use VSYNC OFF in both configurations, theres not really a difference between GSYNC ON 150fps and GSYNC OFF 150fps?

neverendingstory wrote: ↑

07 Jul 2020, 13:13

So assuming I use VSYNC OFF in both configurations, theres not really a difference between GSYNC ON 150fps and GSYNC OFF 150fps?

Correct. Average input lag is the same. The difference is that with gsync ON the latency will be always the same in each region of the screen, while with gsync OFF it will vary: when it gets lower near the bottom of the screen, it gets higher near the top of the screen, depending on where the tearline is located each frame. With gsync ON the tearline is always at the same spot (hidden below the bottom of the visible area of the screen), so there is no such latency variation from frame to frame.