Learn when to enable V-Sync in FSX, how it affects FPS, tearing and input lag, and which frame-rate cap suits boxed and Steam editions.
Enable V-Sync in FSX when screen tearing is visible and your frame rate is reasonably stable. It synchronises frames with the monitor, so it improves presentation rather than rendering speed. It can cap FPS, add slight input lag, and cause judder or sharp frame-rate steps when FSX cannot maintain the chosen refresh cadence.
When should you turn V-Sync on in FSX?
Turn V-Sync on when horizontal tearing is more distracting than its small increase in latency.
- Enable it: when tearing appears while panning, looking around the cockpit or watching scenery move across the screen, especially if FPS remains close to the monitor's refresh rate or a clean divisor of it.
- Leave it off initially: when diagnosing low FPS, severe stuttering or scenery-loading pauses. It is also reasonable to leave it off if you see no tearing and prefer the quickest control response.
A mistake we see constantly is treating V-Sync as an FPS fix. FSX is often limited by work on its main rendering thread, so synchronising the display cannot remove a CPU bottleneck. If the real symptom is low or uneven performance, use our FSX CPU, scenery and traffic tuning checklist rather than expecting V-Sync to cure it.
How does V-Sync affect FSX performance?
V-Sync changes when FSX presents a frame; it does not make that frame quicker to render.
| Setting and situation | Display behaviour | Practical result |
|---|---|---|
| V-Sync off | Frames are presented as soon as they are ready. | Highest reported FPS and lowest latency, but visible tearing is possible. |
| V-Sync on and FSX holds the refresh rate | Output is capped and aligned with monitor refreshes. | Tear-free motion and cleaner panning, with slightly more latency. |
| V-Sync on but FSX misses the refresh cadence | A frame may be repeated while the next refresh is awaited. | Judder or a sudden lower FPS reading; traditional double buffering can produce a 60-to-30 step. |
| V-Sync on with a stable divisor cap | Each rendered frame can be shown for an even number of refresh cycles. | Lower numerical FPS, but often steadier motion in demanding scenery. |
The exact drop depends on the graphics driver, buffering, display mode and Windows composition. A fall from 60 to 30 FPS is common behaviour on a 60 Hz display, but it is not guaranteed on every system. It also does not prove that the computer can render only 30 FPS; synchronisation may be enforcing the lower cadence.
Press Shift+Z until the FSX statistics show FPS, then test while slowly panning across a strong vertical edge such as a terminal or cockpit pillar. An FPS reading equal to the refresh rate means the output is capped, not that V-Sync improved the simulator's underlying speed. Our controlled graphics-setting test method explains how to separate a cap from a genuine CPU or GPU limit.
How do you enable V-Sync in FSX?
FSX: Steam Edition provides an in-game V-Sync option, while boxed FSX normally needs a per-program graphics-driver setting.
- FSX: Steam Edition: open the simulator's display or graphics settings and enable V-Sync. The control was added through a Steam Edition update; our notes for the build that introduced the V-Sync option also cover its interaction with driver settings.
- Boxed FSX: create an application profile for
fsx.exein the NVIDIA, AMD or Intel graphics control panel and set vertical synchronisation to On. Use a program-specific profile rather than changing the global setting.
- Choose one control method. With Steam Edition's option enabled, leave the driver set to application-controlled. With boxed FSX, use the standard driver V-Sync override. Avoid stacking standard, adaptive and fast synchronisation modes.
- Set an achievable Target frame rate. FSX's own limiter is separate from V-Sync and does not remove tearing by itself. Pick a value the simulator can maintain in your normal aircraft and scenery.
- Retest the same flight. Keep the aircraft, airport, weather, traffic and view unchanged. Compare FPS, panning smoothness and control response rather than looking only at the highest number.
- Compare full-screen and windowed modes. Driver overrides may behave differently between them, while Windows may already synchronise a window through its desktop compositor.
Avoid copying undocumented V-Sync entries into FSX.cfg. Their effect varies between editions and patched installations, whereas the Steam option or a dedicated driver profile is easier to reverse and verify.
What frame-rate cap should you use with V-Sync?
Use a frame-rate cap that FSX can sustain and that divides the monitor's refresh rate evenly.
- On a 60 Hz display, use 60 FPS if FSX can hold it in demanding flights; otherwise, a stable 30 FPS usually has cleaner cadence than a fluctuating 40–55 FPS.
- On a 120 Hz display, 60, 40 and 30 FPS are even divisors. Choose the highest one the simulator can hold reliably.
- On a 144 Hz display, 72, 48 and 36 FPS divide evenly, though changing the display to 120 Hz can make 30 or 60 FPS targets easier to match.
Do not choose 40 FPS on a 60 Hz monitor merely because an average benchmark shows 40; those frames cannot be distributed evenly across 60 refreshes. Treat FSX's Target frame rate as a ceiling rather than a guarantee. If its limiter itself produces uneven pacing, a per-application driver cap is an alternative, but use only one limiter at a time.
Why does V-Sync still stutter or fail to remove tearing?
Persistent stutter or tearing usually indicates mismatched frame pacing, a conflicting override, the wrong executable profile or a problem unrelated to synchronisation.
- Confirm that the driver profile targets the copy of
fsx.exeyou actually launch, particularly if boxed and Steam editions are both installed. - Verify the monitor is running at the refresh rate used to choose the FPS cap.
- Remove conflicting adaptive, fast or application overrides before testing standard V-Sync again.
- Lower the target to a stable divisor if FPS repeatedly falls just below the refresh rate.
- If pauses coincide with new scenery, AI traffic or complex add-on systems, treat them as loading or CPU stalls rather than a V-Sync fault.
For a typical 60 Hz setup, we recommend enabling V-Sync only when tearing is visible, then pairing it with 60 FPS if FSX stays there or 30 FPS if it cannot. If tearing is absent or frame pacing becomes worse, leave V-Sync off. The best setting is the one that remains even in your heaviest normal flight, not the one showing the highest momentary FPS.