acer kb272 screen keeps flickering at 120hz but is fine at 60hz, adaptive sync is on

Diagnosis

The flickering observed on the Acer KB272 when pushed to 120Hz is typically a result of "signal instability" caused by bandwidth saturation. While the monitor is rated for 120Hz, the combination of a 1920x1080 resolution, high refresh rate, and the overhead required for Adaptive-Sync (FreeSync/G-Sync compatible) creates a high-frequency data stream that is susceptible to electromagnetic interference or voltage drops in the cable.

When Adaptive-Sync is enabled, the monitor constantly adjusts its refresh rate to match the GPU's output. At 120Hz, the timing windows are extremely tight. If the cable cannot maintain a consistent signal integrity, the monitor loses synchronization for a fraction of a second, resulting in a rapid flicker or a momentary black screen. You can confirm this is a bandwidth issue if the flickering occurs more frequently during high-motion gaming scenes or if the flicker disappears immediately when you switch to a static 60Hz fixed refresh rate.

How to Fix It

To resolve this, you need to stabilize the signal by adjusting the refresh rate and ensuring the handshake between the GPU and the KB272 is optimized. Follow these steps:

1. Right-click on your desktop and select Display settings.
2. Scroll down and click on Advanced display.
3. Under the "Choose a refresh rate" dropdown menu, select 100Hz. This provides a significant smoothness upgrade over 60Hz while reducing the bandwidth load by nearly 17% compared to 120Hz, which usually eliminates the flicker.
4. If 100Hz is stable, open your GPU control panel (NVIDIA Control Panel or AMD Radeon Software).
5. Navigate to the G-SYNC/FreeSync tab and ensure "Enable G-SYNC/FreeSync" is checked, but specifically select "Enable for full screen mode" rather than windowed mode to reduce driver overhead.
6. Restart your computer to commit the timing changes to the monitor's internal firmware.

If That Didn't Work

• Replace the HDMI/DisplayPort Cable: The cable bundled with the KB272 is often a basic version. Upgrade to a Certified Premium High Speed HDMI 2.1 or a VESA Certified DisplayPort 1.4 cable. A cable with better shielding prevents the EMI (electromagnetic interference) that causes flickering at high refresh rates.
• Disable Adaptive-Sync in OSD: Use the physical buttons on the bottom of the monitor to enter the On-Screen Display (OSD) menu. Navigate to Gaming and toggle Adaptive-Sync to OFF. If the flickering stops at 120Hz without Sync, the issue is a compatibility mismatch between the monitor's variable refresh rate range and your GPU's driver.
• Update GPU Drivers using DDU: Perform a "Clean Install" of your graphics drivers. Download Display Driver Uninstaller (DDU), boot into Safe Mode, wipe the existing drivers, and install the latest version from the manufacturer's website. This clears corrupted "EDID" profiles that may be telling the monitor to use an unsupported timing.
• Change Power Source: Ensure the monitor is plugged directly into a wall outlet or a high-quality surge protector. Using a cheap, overloaded power strip can cause voltage fluctuations that manifest as screen flickering when the monitor is drawing maximum power at 120Hz.

Heads Up

• Avoid using HDMI-to-DP adapters or hubs; these introduce signal latency and bandwidth bottlenecks that make 120Hz unstable on the KB272.
• Check for nearby high-power electronics (like large speakers or space heaters) near the monitor cable, as these can cause the signal interference that leads to flickering.
• If you use a 100Hz setting, remember to update your in-game settings to match, otherwise, the GPU may try to force 120Hz, causing the flicker to return.
• Periodically check the monitor's firmware via the Acer support site to see if a timing update is available for the KB272 series to improve Adaptive-Sync stability.