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FPS locked at 320 on a 360 Hz G-SYNC Pulsar monitor

Last verified October 2026Tested against GeForce Game Ready Driver 617.42 WHQL (6 October 2026) and earlier Release 615 drivers, Fixed in GeForce Hotfix Driver 617.70 (mid-October 2026), which is not WHQL, 27-inch QHD 360 Hz G-SYNC Pulsar monitors, for example the ASUS ROG Strix XG27AQNGV, Windows 10 and Windows 11, 64-bitWell documented

This is a confirmed NVIDIA driver bug, not your frame limiter. NVIDIA tracks it as 6408986 - "When gaming on a 360Hz G-SYNC Pulsar monitor, FPS may drop to 320FPS" - and fixed it in the 617.70 hotfix driver. That fix is in no WHQL driver: NVIDIA missed the QA cutoff for 617.42 and posted the hotfix only as a download link in its G-SYNC Pulsar forum, so 617.42's release notes do not mention the bug at all. Install the hotfix. Before you do, rule out an ordinary cap - V-Sync, Reflex, an in-game limiter or the NVIDIA App's Max Frame Rate - because from inside a game those look identical.

Start here

  1. Rule out an ordinary frame cap first
  2. Install the 617.70 hotfix driver

A 360 Hz QHD G-SYNC Pulsar panel that settles at exactly 320-321 FPS looks like a frame-limiter problem, and that is where most advice sends you. It is not. NVIDIA has acknowledged the bug with its own bug ID and shipped a driver that fixes it - but only as a hotfix build posted in a forum thread, which is why searching the release notes, the support site or the driver download page turns up nothing.

Symptoms

  • Frame rate starts at 360 FPS and then drops to 320-321 FPS, typically within five minutes of play, and stays there
  • The cap holds with V-Sync off and NVIDIA Reflex off
  • The monitor's own built-in FPS counter shows the same drop, so it is not an overlay misreading the frame rate
  • Reproducible outside games - NVIDIA's own Pendulum Demo shows it with the FPS slider set above 360
  • Seen on 27-inch QHD 360 Hz G-SYNC Pulsar monitors such as the ASUS ROG Strix XG27AQNGV

Why this happens

A Release 615 driver bug that NVIDIA has acknowledged and fixed in a hotfix

NVIDIA lists the symptom verbatim as one of the two bugs fixed by the 617.70 hotfix driver: "When gaming on a 360Hz G-SYNC Pulsar monitor, FPS may drop to 320FPS [6408986]". NVIDIA also says why the fix is hard to find - it missed the QA cutoff for 617.42, the Game Ready driver published on 6 October 2026, and NVIDIA has said these fixes will not go into the main driver until it can do more extensive QA. The 617.42 release notes therefore never mention the bug, in either the fixed or the open list. NVIDIA has not published a root cause for why the number lands on 320.

Install the 617.70 hotfix driver

Windows Multi-Plane Overlay interference - a reader's finding that fits NVIDIA's own documentation

One reporter on an RTX 5090 worked the problem down to Windows Multi-Plane Overlay (MPO), which NVIDIA defines as the feature that lets the GPU compose image layers independently before they reach the display. After ruling out V-Sync, Reflex, the NVIDIA overlay and a clean driver install, they disabled MPO and the cap disappeared. They also report that connecting a second display - a workaround said to help on RTX 40, 30 and 20-series cards by changing how MPO behaves - did nothing on the 50-series, and inferred that Blackwell handles multi-monitor MPO differently. NVIDIA's own MPO article says exactly that: from Release 610 drivers, MPO 'is now supported on all monitors in multi-monitor configurations on Blackwell GPUs'. So the mechanism is plausible and the generational difference is documented. What is not documented is MPO causing this cap - NVIDIA has never said so, and it shipped a driver fix instead. Treat MPO as the last thing to try, not the explanation.

Last resort: turn off Multi-Plane Overlay with NVIDIA's registry file

Fixes

Rule out an ordinary frame cap first

about 10 min

A driver-level or in-game limiter produces a hard ceiling that looks exactly like this from inside the game, and it is the one cause you can fix in a minute.

Applies to: Any 360 Hz G-SYNC Pulsar monitor

  1. Check the game's own settings for a frame-rate limit and for V-Sync, and turn both off for the test.
  2. In the NVIDIA App or NVIDIA Control Panel, check Max Frame Rate and Vertical sync under Manage 3D Settings - both globally and in the per-game profile, which overrides the global one.
  3. Turn NVIDIA Reflex off in the game temporarily. Reflex caps frame rate on purpose when it is managing latency, and the reporter who diagnosed this bug had to rule it out explicitly.
  4. Watch the monitor's built-in FPS counter rather than an overlay, so you are reading the refresh rate the panel is actually receiving.
  5. If you want a game-independent test, launch NVIDIA's Pendulum Demo executable directly rather than through its configuration utility, confirm G-SYNC is checked in the top-left, and set the FPS slider to at least 400. The reporter saw the counter start at 360 and lock to 320-321 within five minutes.

Reported to work by one user; not confirmed by the vendor.

Source: NVIDIA GeForce Forums, NVIDIA GeForce Forums

Install the 617.70 hotfix driver

about 15 min

This is NVIDIA's own fix for the bug, and it exists in no WHQL release - only as a download posted in NVIDIA's G-SYNC Pulsar forum.

Applies to: 360 Hz QHD G-SYNC Pulsar monitors, Windows 10 and Windows 11, 64-bit, Desktop and notebook GeForce GPUs on the Release 615 branch

  1. Download GeForce Hotfix Driver 617.70 from NVIDIA's own download host. The link NVIDIA posted is:
    https://international.download.nvidia.com/Windows/617.70hf/617.70-desktop-notebook-win10-win11-64bit-international-dch.hf.exe
  2. Install it over your current driver and reboot, then re-run whichever test showed the cap.
  3. Know what you are installing. NVIDIA's own policy for hotfix drivers is that they are 'beta, optional and provided as-is', run through 'a much abbreviated QA process', and that 'the safest option is to wait for the next WHQL certified driver'. A hotfix is the current WHQL driver - here 617.42 - plus a small number of targeted fixes, and NVIDIA takes it down once those fixes reach an official release. If that is not acceptable to you, stay on 617.42, but be aware NVIDIA has said these Pulsar fixes will not reach the main driver until it completes more QA, so there is no certified release to wait for yet.
  4. If you are also seeing occasional black flashes at 360 Hz, the same hotfix covers NVIDIA's bug 4846825 - but NVIDIA says it fixes some, not all, cases. For the rest NVIDIA's workaround is Manage 3D Settings > Power Management Mode > Prefer Maximum Performance, and it only takes effect after a reboot.

Confirmed by the vendor.

Source: NVIDIA GeForce Forums, NVIDIA GeForce Forums, NVIDIA, NVIDIA

Last resort: turn off Multi-Plane Overlay with NVIDIA's registry file

Advancedabout 10 min

One reporter traced this cap to MPO and removed it this way. NVIDIA publishes the toggle itself, but has never named MPO as the cause of this bug.

Applies to: Windows 11, 360 Hz QHD G-SYNC Pulsar monitors, Most relevant on RTX 50-series (Blackwell) cards, where a second display does not change MPO behaviour

Before you do this

This edits the Windows registry and turns off a display composition feature that Windows and your GPU use by default. NVIDIA documents the toggle but has never endorsed it as a fix for this bug, and disabling MPO is widely reported to break rendering in other games. Keep mpo_restore.reg so you can reverse it, and prefer the 617.70 hotfix.

  1. Only do this if the hotfix is unavailable to you or did not help. NVIDIA shipped a driver fix for this bug; that is the supported route and it does not touch your registry.
  2. Open NVIDIA's own article 'What is Multi-Plane Overlay (MPO) in Windows 11' and download mpo_disable.reg from the Attachments section. Use NVIDIA's file rather than a third-party utility or a hand-written key - the value has changed between Windows builds, which is how people end up disabling nothing or breaking composition.
    https://nvidia.custhelp.com/app/answers/detail/a_id/5157/~/what-is-multi-plane-overlay-(mpo)-in-windows-11
  3. Double-click the file, accept the prompt to add it to the registry, and restart the PC. The change does nothing until you restart.
  4. Re-run your test. If the cap is gone, that is a real result - but keep mpo_restore.reg, from the same page, so you can put MPO back.
  5. Put MPO back if anything else regresses. Disabling it forces Windows onto the older composition path, and it is widely reported to cause its own rendering problems in some games. NVIDIA also notes MPO wants Windows build 26100.7705 or 26200.7705 or later to work properly, so an out-of-date Windows is worth ruling out before you disable anything.

Reported to work by one user; not confirmed by the vendor.

Source: NVIDIA GeForce Forums, NVIDIA

Known issues

  • NVIDIA bug 6408986 - "When gaming on a 360Hz G-SYNC Pulsar monitor, FPS may drop to 320FPS". NVIDIA says hotfix 617.70 fixes it. The bug is not listed in the 617.42 release notes.

    Affects 617.42 WHQL and earlier Release 615 drivers, Fixed in GeForce Hotfix Driver 617.70 · Status: fixed

  • NVIDIA bug 4846825 - occasional black flash during gameplay on a QHD monitor at 360 Hz. The 617.70 hotfix fixes some but not all cases; for the rest NVIDIA's workaround is Power Management Mode set to Prefer Maximum Performance, after a reboot.

    Affects 617.42 WHQL, Partly fixed in GeForce Hotfix Driver 617.70 · Status: workaround only

  • Worth knowing if you are told to use that workaround: 617.42's only documented open issue is bug 6007998, "Prefer Maximum Performance Power Management Mode may not be applied correctly" - the same setting NVIDIA offers as the black-flash workaround.

    Affects 617.42 WHQL · Status: open

  • G-SYNC and Pulsar not working after the monitor wakes from sleep is a separate, still-open bug. NVIDIA says it has a reproduction and that a fixed driver has no ETA; the hotfix does not address it.

    Affects 617.42 WHQL and earlier, Not fixed in GeForce Hotfix Driver 617.70 · Status: open

If none of this worked

If your frame rate is unstable rather than pinned at 320, this is not your bug - stuttering after a driver update is a different problem. If the screen flashes dark at 360 Hz, that is NVIDIA's bug 4846825 above, or the separate 8-bit flicker that has run through the Release 615 branch. If G-SYNC never engages at all in a borderless window, two settings have to agree and neither is a driver bug. And if the panel goes black after waking from sleep, see the open sleep bug above, or - if there is no picture at all over DisplayPort - the wake failure NVIDIA fixed in 617.14.

Common questions

Is 617.70 a Game Ready driver?
No. It is a hotfix built on 617.42 WHQL and distributed by NVIDIA as an optional beta, as-is, outside normal WHQL certification. NVIDIA has said these two Pulsar fixes will not go into the main driver until it can do more extensive QA, so there is no certified release carrying the fix yet.
Why does nothing about this appear in the release notes?
Because NVIDIA finished the fix after the 617.42 QA cutoff and published it in a forum thread instead. Its words: "Unfortunately we missed the QA cutoff to get these fixes in the 617.42 main driver published a few days ago." The 617.42 notes list one open issue and one fixed gaming bug, and neither is this.
Should I disable Multi-Plane Overlay instead?
Not first. NVIDIA has shipped an actual fix for this bug, and the hotfix does not touch your registry. If you do go that way, use NVIDIA's own mpo_disable.reg from its MPO article rather than a third-party utility - the registry value has changed between Windows builds. And know the trade: disabling MPO forces the older composition path and is widely reported to break rendering in other games. NVIDIA documents how to turn MPO off; it has never said MPO causes this cap.
Does my monitor firmware matter?
Keep it current - 1.1.10 is the firmware NVIDIA links from its Pulsar changelog, and it carries Pulsar behaviour changes of its own. But nothing NVIDIA has published says firmware causes or fixes the 320 FPS cap, so do not expect a firmware update to resolve it.

Did this fix work?

If a step is wrong, outdated, or did not help, telling us is the fastest way to get it corrected. Reports are reviewed before new articles.

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Related problems

Sources

  • Pulsar Hotfix DriverOfficial

    NVIDIA GeForce Forums · Forum · checked Oct 16, 2026

    • NVIDIA Staff announcement of hotfix 617.70, the two bug IDs it fixes, the missed QA cutoff for 617.42, the partial nature of the black-flash fix, and the Prefer Maximum Performance workaround requiring a reboot
  • QHD 360 Pulsar Monitors ChangelogOfficial

    NVIDIA GeForce Forums · Forum · checked Oct 16, 2026

    • NVIDIA's stickied Pulsar changelog: the hotfix bug IDs, that the fixes stay out of the main driver pending more QA, the open 'no G-SYNC after monitor sleep' bug with repro and no ETA, and monitor firmware 1.1.10
  • Release Notes: NVIDIA Release 615 Driver for Windows, Version 617.42 (RN-08399-617.42_v01)Official

    NVIDIA · Release notes · checked Oct 16, 2026

    • 617.42's complete fixed and open issue lists, which contain neither Pulsar bug, and open issue 6007998 on Prefer Maximum Performance not being applied correctly
  • GeForce Hotfix Display Driver version 616.86Official

    NVIDIA · Knowledge base · checked Oct 16, 2026

    • NVIDIA's standing policy text for hotfix drivers: beta, optional, provided as-is, abbreviated QA, the safest option being to wait for the next WHQL certified driver, and hotfixes being taken down once their fixes reach an official release
  • What is Multi-Plane Overlay (MPO) in Windows 11Official

    NVIDIA · Knowledge base · checked Oct 16, 2026

    • NVIDIA's definition of MPO, its official mpo_disable.reg and mpo_restore.reg files and procedure, the Blackwell multi-monitor MPO change from Release 610 drivers, and the minimum Windows builds
  • 320 FPS Lock Bug: Cause and SolutionCommunity report

    NVIDIA GeForce Forums · Forum · checked Oct 16, 2026

    • One reader's reproduction and diagnosis: V-Sync and Reflex ruled out, the Pendulum Demo repro, the 320-321 FPS lock within five minutes, MPO identified as the apparent cause, and the second-display workaround failing on an RTX 5090
  • no G-SYNC/Pulsar after monitor sleepCommunity report

    NVIDIA GeForce Forums · Forum · checked Oct 16, 2026

    • NVIDIA Staff asking for a reliable reproduction of the post-sleep G-SYNC failure, and one reader's detailed repro and two workarounds