What FPS should I cap at with G-Sync?
At least 3 fps below your refresh rate with a manual limiter, which is Blur Busters' tested minimum. If Reflex or Ultra Low Latency Mode is on with G-Sync and V-Sync, the driver sets a lower cap for you (about 224 at 240 Hz) and you should leave it alone. The gap between the two answers grows with refresh rate, and it is smaller than it looks: about a quarter of a millisecond.
Cap at least 3 fps below your refresh rate: 141 at 144 Hz, 237 at 240 Hz. That is the minimum Blur Busters arrived at by testing, and it keeps G-Sync engaged. If Reflex or Ultra Low Latency Mode is on together with G-Sync and V-Sync, ignore that number, because the NVIDIA driver caps lower on its own: about 138 fps at 144 Hz and 224 at 240 Hz. Leave that cap where it is. The two numbers drift further apart as refresh rate rises, and the reason is simple arithmetic.
Why two answers circulate
The "3 below" rule is from Blur Busters' G-SYNC 101 series. Its author jorimt tested on a 240 Hz Acer Predator XB252Q with a 1000 fps camera, in Overwatch and CS:GO, and found that "just 2 FPS below the refresh rate is indeed still enough to avoid the G-SYNC ceiling", and that "this number does not change, regardless of the maximum refresh rate in use". The recommendation adds one frame for safety: "a -3 FPS limit is the safest bet". The settings page phrases it as "(a minimum of) 3 FPS limit below display's maximum refresh rate".
The other number comes from the driver. NVIDIA's System Latency Optimization Guide says that keeping V-Sync on while using Reflex or Ultra Low Latency Mode "will automatically cap the framerate below the refresh rate, preventing VSYNC backpressure". NVIDIA does not publish the values. Blur Busters' optimal settings page lists them as approximately 59 fps at 60 Hz, 97 at 100 Hz, 116 at 120 Hz, 138 at 144 Hz and 224 at 240 Hz. Players who set 237 by hand, turn Reflex on and watch their counter stop at 224 conclude that one of the two is wrong. Neither is.
The two caps, in milliseconds
Both caps exist for the same reason. The 101's FAQ explains that "frametime variances" make limiters "occasionally 'overshoot' the set limit", and one frame faster than the refresh rate puts G-Sync above its range. What protects you is the gap between the cap's frame time and the refresh interval, so we measured both rules in that unit.
| Refresh rate | Manual cap (-3) | Margin (ms) | Automatic cap | Margin (ms) |
|---|---|---|---|---|
| 60 Hz | 57 | 0.877 | 59 | 0.282 |
| 100 Hz | 97 | 0.309 | 97 | 0.309 |
| 120 Hz | 117 | 0.214 | 116 | 0.287 |
| 144 Hz | 141 | 0.148 | 138 | 0.302 |
| 240 Hz | 237 | 0.053 | 224 | 0.298 |
| 360 Hz | 357 | 0.023 | 326 | 0.290 |
The pattern is the finding. Every automatic cap sits 0.28 to 0.31 ms of frame time below the refresh interval, whatever the refresh rate. A fixed 3 fps offset does the opposite: it is generous at 60 Hz and leaves 0.05 ms at 240 Hz and 0.02 ms at 360 Hz, because the same 3 fps is a smaller slice of a shorter frame. That is why the driver's offset grows from 1 fps at 60 Hz to 16 fps at 240 Hz. jorimt describes it the same way in the 101's comments: "The higher the physical refresh rate, the larger the auto limit's offset." The 360 Hz figure is from a Blur Busters forum report of Overwatch in March 2021 stopping at 326 fps with Ultra Low Latency on.
What the bigger margin costs
Very little. Capping at 224 instead of 237 on a 240 Hz panel makes each frame 0.245 ms longer. At 144 Hz, 138 instead of 141 costs 0.154 ms. Compare that with what the cap prevents: above the ceiling, G-Sync falls back to V-Sync and brings back its latency penalty, as our VRR guide explains. If you want the numbers for your own frame rate, our fps and refresh calculator does the frame-time maths.
Which cap to use
| Your setup | Cap at | Why |
|---|---|---|
| Reflex or Ultra Low Latency on, G-Sync on, V-Sync on in the control panel | Nothing; the driver caps for you | A manual cap above the automatic one does nothing |
| No Reflex, 60 to 144 Hz | Refresh minus 3 | Blur Busters' tested minimum, already near a 0.15 ms margin or more |
| No Reflex, 240 Hz or above | Refresh minus 3 to start; drop toward the automatic figure if you see the counter hit refresh | The 3 fps margin is under 0.06 ms; going lower costs about 0.25 ms |
| 480 Hz, no published automatic figure | About 420 fps for the same 0.3 ms margin | Derived from the table, not observed |
Use the game's own limiter if it has one. Blur Busters recommends an in-game or config file limiter first, then RTSS or NVIDIA's "Max Frame Rate" (added in driver 441.87) when there is none. Our Reflex and Anti-Lag page explains why a capped GPU also keeps the render queue empty. Keep G-Sync running in a mode the driver can sync: NVIDIA notes that control panel V-Sync "will only work for Fullscreen applications", so in a window use in-game V-Sync, and check your present mode.
The verdict
- Reflex or Ultra Low Latency on, with G-Sync and V-Sync: let the driver cap. About 138 at 144 Hz, 224 at 240 Hz.
- Manual limiter: at least 3 below refresh. That is the tested minimum, not a target to beat.
- At 240 Hz and above, a lower manual cap buys margin for about a quarter of a millisecond.
Where this stops applying
Blur Busters tested a G-Sync monitor with a hardware module on one 240 Hz panel in 2017, and its settings page says G-Sync Compatible behaviour "may vary"; its FAQ still applies the 3 fps minimum to G-Sync Compatible FreeSync monitors. The automatic caps are approximate, NVIDIA does not publish them, and the 360 Hz value is one user's report. We found no AMD documentation of an equivalent automatic cap, so on a Radeon card use the manual rule. Blur Busters notes Ultra Low Latency Mode is not supported in Vulkan. None of this matters if your frame rate never reaches your refresh rate: then G-Sync never hits its ceiling, and the cap that counts is the one that keeps your GPU below full load.
Frequently asked questions
Is 3 fps below refresh enough for G-Sync?
Yes, on the systems Blur Busters tested. Its G-SYNC 101 tests on a 240 Hz G-Sync monitor found 2 fps below refresh was enough to avoid the G-Sync ceiling, "regardless of the maximum refresh rate in use", and it recommends a minimum of 3 fps to allow for limiters that overshoot.
Why does Reflex cap my fps at 224 on a 240 Hz monitor?
Because G-Sync, V-Sync and Reflex are all on. NVIDIA's latency guide says that combination will "automatically cap the framerate below the refresh rate" to prevent V-Sync backpressure. Blur Busters lists the result as about 224 fps at 240 Hz and 138 fps at 144 Hz. Turning V-Sync off removes the automatic cap.
What fps cap for a 144 Hz G-Sync monitor?
141 fps with a manual limiter, Blur Busters' minimum offset of 3 fps. With Reflex or Ultra Low Latency Mode on alongside G-Sync and V-Sync, the driver caps at about 138 fps instead, and a manual cap above that has no effect.
Should I use the in-game limiter or the NVIDIA control panel?
The in-game limiter if the game has one. Blur Busters recommends an in-game or config file limiter first, with RTSS or NVIDIA's Max Frame Rate setting (added in driver 441.87) only when the game has none.
Does capping fps below refresh add input lag?
Very little. Each frame takes slightly longer, by the difference in frame time: 0.05 ms going from 240 to 237 fps, and 0.25 ms going from 237 to 224. Hitting the refresh ceiling with V-Sync on brings back V-Sync's input lag, which is what the cap prevents.