PG27UCDM G‑SYNC Range 48–240 Hz – LFC Engaging at 60 Hz

[USERMAC]

The PG27UCDM is specified with a G‑SYNC/VRR range of 48–240 Hz. However, Low Framerate Compensation (LFC) is engaging at 60 Hz, even though the VRR floor is listed as 48 Hz. This behavior can be observed directly using the PG27UCDM’s built‑in OSD FPS/Hz counter: once frame rates drop below 60 FPS, the monitor switches into LFC instead of continuing native VRR operation.

For gamers, this means that sub‑60 FPS gameplay does not benefit from true VRR smoothing. Instead, frames are doubled, which can introduce cadence artifacts. On a 4K display, where dips below 60 FPS are common in demanding titles, having a proper 48 Hz VRR floor is essential for smooth and consistent gameplay.

If you own a PG27UCDM and want to confirm this behavior, here are the steps:

1. Enable the OSD FPS/Hz Counter

   • Go into the monitor’s on‑screen display (OSD) menu.

   • Turn on the built‑in FPS/Hz counter so you can see the refresh rate in real time.

2. Cap Your Framerate Below 60 FPS

   • Use RTSS (RivaTuner Statistics Server), an in‑game limiter, or another tool to lock your framerate to ~55 FPS.

   • Make sure V‑Sync is off and G‑SYNC/VRR is enabled.

3. Observe the OSD Counter

   • At ~55 FPS, the OSD should ideally show ~55 Hz if VRR is working down to 48 Hz.

   • Instead, you’ll see the counter jump to ~110 Hz — this indicates LFC is activating at 60 Hz, not 48 Hz.

4. Confirm Across Setups

   • Try both DisplayPort 2.1 and HDMI 2.1 connections.

   • If possible, test on different GPUs (NVIDIA and AMD) to show the behavior is consistent.

5. Share Your Results

   • Post a screenshot of your OSD counter at ~55 FPS.

   • Mention your GPU, driver version, and connection type.  Real Frame Rate/FPS 55 With LFC making it 110 when is should be 55Hz

Nvidia Official  GeForce G-SYNC Monitors: Manufacturers & Specs

ASUS_PG27UCDM_UM-EN.pdf

[ROGoa62bibpawmx]

Hey. I'm having the same problem. I'm currently on the latest drivers available for my Nvidia card (591.59) and I've tried 2 different monitor firmware versions (MCM105, and MCM107). The LFC kicks in at around 59/60fps for the Hz to be doubled. Have you figured anything out to fix it or are ASUS even aware?

[ROGoa62bibpawmx]

I've done some more testing and this only happens with Nvidia drivers 591.44 and 591.59. I just tried older drivers (581.80, 581.94) and the LFC didn't enable when my game was locked to 60fps like it did before. I also confirmed, with ALL driver versions listed, that the LFC range remained unchanged (48-240). This was verified using Custom Resolution Utility. So it looks it it's something on Nvidia's driver end.

[USERMAC]

Thanks for digging into this — your testing lines up with what I’m seeing on my side as well.

I also checked multiple NVIDIA driver branches, and the behaviour is identical: • 591.44 / 591.59 → LFC triggers early at ~59/60 FPS • Older 58x drivers → VRR behaves correctly and does not jump into LFC at 60 FPS

So your results match mine: the monitor’s reported VRR range (48–240 Hz) stays the same across all drivers, but the actual behaviour changes depending on the driver version.

The key point is that the PG27UCDM’s own OSD counter confirms what’s happening: • At ~55 FPS, the refresh rate should track at ~55 Hz • Instead, on 591.xx drivers it jumps to ~110 Hz, which means LFC is being forced early

I’ve tested this across: • DisplayPort 2.1 and HDMI 2.1 • Multiple GPUs • Multiple firmware versions (MCM105, MCM107)

The result is consistent: only the newer NVIDIA drivers force LFC at 60 Hz.

At this stage it does look like something changed on NVIDIA’s end, but it would still be good for ASUS to confirm whether the monitor’s true VRR floor is 48 Hz or if the driver is overriding it for some reason. If this is unintended behaviour, hopefully it can be corrected in a future driver or firmware update.

My Current Theory (Based on Testing So Far)

Based on the behaviour I’m seeing, it looks like the newer NVIDIA 591.xx drivers may be applying their own driver‑level anti‑flicker system, similar to how ASUS’s OLED Anti‑Flicker modes work. On the PG27UCDM, those modes raise the VRR floor to reduce flicker:

• Off: 48–240 Hz

• Middle: 80–240 Hz

• High: 140–240 Hz

With driver 591.59, the monitor behaves as if the VRR floor is being raised automatically — even when Anti‑Flicker is set to Off. This would explain why LFC is now triggering far earlier than it should.

In other words, the NVIDIA driver may be enforcing its own minimum VRR threshold (similar to ASUS’s Middle/High settings) to reduce flicker and blackouts on OLED panels. If that’s what’s happening, the driver is effectively overriding the monitor’s advertised 48 Hz VRR floor, even though NVIDIA has not said anything publicly about this.

[USERMAC]

My Current Theory (Based on Testing So Far)

Based on the behaviour I’m seeing, it looks like the NVIDIA drivers may be applying their own driver‑level anti‑flicker system, similar to how ASUS’s OLED Anti‑Flicker modes work. On the PG27UCDM, those modes raise the VRR floor to reduce flicker:

• Off: 48–240 Hz

• Middle: 80–240 Hz

• High: 140–240 Hz

With driver 591.59, the monitor behaves as if the VRR floor is being raised automatically — even when Anti‑Flicker is set to Off. This would explain why LFC is now triggering far earlier than it should.

In other words, the NVIDIA driver may be enforcing its own minimum VRR threshold (similar to ASUS’s Middle/High settings) to reduce flicker and blackouts on OLED panels. If that’s what’s happening, the driver is effectively overriding the monitor’s advertised 48 Hz VRR floor, even though NVIDIA has not said anything publicly about this.

[ROGoa62bibpawmx]

Thanks for the reply, mate. I agree with everything you've said, honestly. Including your theory about Nvidia implementing their own form of 'anti-flicker' tech on a driver level - it's the only thing that really makes sense.

I've raised a ticket about this issue with ASUS and Nvidia, and provided as much evidence as I can about what's happening. I've also opened a proper bug report with Nvidia so hopefully, if it does get flagged, it gets added to a list of upcoming fixes down the line.

If I hear anything back from either party, or discover something new myself, I'll add to this forum post. Thanks again for your help, too.

[ROGoa62bibpawmx]

@USERMAC - NV support have asked me to test this before they pass the issue over to another department. I've tried it (to no avail) but I was wondering if you could also give it a go and report back. It's probably something you've already done but this is what they suggested:

> Sometimes the VRR floor scales based on the maximum refresh rate set in Windows.
- Go to NVIDIA Control Panel > Change Resolution.
- Lower your maximum refresh rate from 240Hz to 120Hz or 144Hz as a test.
- Check if LFC still triggers at 60fps or if it correctly drops to the 48Hz floor.

Thanks for the help.

[USERMAC]

PG27UCDM – VRR/LFC Behaviour at 120 Hz (Test Findings)

Refresh rate configuration: The PG27UCDM cannot be set to 140 Hz, but it can be set to 120 Hz without issue.

Observed VRR/LFC behaviour at 120 Hz:

• With the monitor running at 120 Hz, setting a 50 FPS cap in the NVIDIA Pendulum tester immediately triggers LFC, doubling the refresh rate to 100 Hz.

• Increasing the cap to 51 FPS restores normal VRR operation, with no LFC activation.

Implication: This behaviour indicates an effective VRR floor of ~51 FPS, not the 48 FPS advertised in the EDID and reported by the G‑Sync tester. The monitor is entering LFC earlier than expected, reducing the usable VRR range and causing unnecessary frame‑doubling in the 48–50 FPS region.

[ROGoa62bibpawmx]

Thanks for testing. Interesting. So, if you set the FPS cap to 60fps in NV Pendulum with the refresh rate set to 120Hz, it doesn't trigger LFC to change the Hz to ~120? It's only around the ~50fps range that triggers LFC and VRR to set the refresh rate to ~110? I'll send this information back to NV support.

[USERMAC]