DIAGNOSIS Windows HDR calibration is incorrect or HDR is active in SDR content. The 27GN950-B has an HDR peak brightness of ~600 nits and requires precise settings to avoid a washed-out appearance.
FIX First, enable HDR only when consuming HDR content. Turn it off for desktop use. In Windows, go to Settings > System > Display > Use HDR. Toggle to Off. For HDR content, toggle it On. Then, run the Windows HDR Calibration app from the Microsoft Store. Follow the steps precisely. Set the peak brightness slider to 600 nits. Save the profile.
IF THAT DIDN'T WORK The monitor's own HDR mode must be set correctly. Press the joystick. Go to Picture > Select Mode. Choose 'Gamer 1' or 'Gamer 2'. Then, navigate to Picture > HDR Effect. Set it to On. Do not use the 'Vivid' or 'Reader' modes for HDR. In the NVIDIA Control Panel, under 'Adjust video color settings', set 'With the NVIDIA settings' and ensure the dynamic range is set to 'Full'.
HEADS UP This monitor uses DisplayHDR 600 certification, which is edge-lit. Expect elevated black levels and less impactful HDR compared to Mini-LED or OLED. The 'washed out' look in desktop mode is normal; HDR is designed for mastered content, not the Windows UI.