DIAGNOSIS Windows is defaulting to a generic display driver or a basic resolution profile. You need to manually create a custom resolution with the correct timing or select the native 100Hz option in your graphics control panel.
FIX Force the setting in your GPU software, not Windows Display Settings.
- For NVIDIA: Right-click desktop > NVIDIA Control Panel > 'Change resolution' on the left. Under 'Refresh rate', select '100Hz'. If it's not listed, click 'Customize', then 'Create Custom Resolution', set refresh to 100Hz, and test.
- For AMD: Right-click desktop > AMD Software: Adrenalin Edition > Gaming > Display. Toggle 'Custom Resolution' on, set Refresh Rate to 100Hz, and create.
- Ensure you are using the DisplayPort cable that came with the monitor or a certified high-speed DisplayPort 1.2 cable. HDMI may cap at 60Hz at 1080p on some configurations.
IF THAT DIDN'T WORK Your GPU might be old and not support 100Hz over your chosen connection. Check your GPU's spec sheet for its maximum supported refresh rate over DisplayPort/HDMI.
HEADS UP AMD FreeSync only activates within a specific refresh range (e.g., 48-100Hz). If your game's FPS dips below that, the screen may stutter. Enable FreeSync in both the monitor's OSD ('Game' menu) and your AMD graphics software.