Samsung TV & Audio QN65QN90CAFXZA 65" Class QN90C Neo QLED 4K Smart TV MODE NOT SUPPORTED Error Fix: Unsupported Input Resolution / Refresh Rate

Error code MODE NOT SUPPORTED on the Samsung TV & Audio QN65QN90CAFXZA 65" Class QN90C Neo QLED 4K Smart TV means: Unsupported Input Resolution / Refresh Rate. TV displays "Mode Not Supported" — input signal has an unsupported resolution, refresh rate, or color space. Change output resolution on the source device. For 4K@120Hz, use the HDMI port labeled "4K 120Hz" (typically HDMI 4 on 2023 models). Enable Input Signal Plus: Settings → General → External Device Manager → Input Signal Plus → toggle on for the specific port. Without Input Signal Plus, the port is limited to 4K@60Hz SDR. For PC connections, ensure graphics card output matches a supported TV mode.

The most successful fix is "Replace or Repair HDMI Board and Verify Firmware Compatibility" (hard difficulty, ~60 minutes). Estimated DIY cost: $0-$15. HomeMD has 2 community-ranked fixes for this error.

This error is rated medium severity. It should be addressed soon, but your appliance may still function in a limited capacity.

Yes — the top-ranked community fix ("Replace or Repair HDMI Board and Verify Firmware Compatibility") is rated hard difficulty and takes about 60 minutes. Tools needed: T20 Torx screwdriver, Plastic pry tool, Multimeter.

DIY cost: $0-$15. Professional repair typically costs $150-$250. Many homeowners save money by trying the top-ranked community fix first.

The Samsung TV & Audio QN65QN90CAFXZA 65" Class QN90C Neo QLED 4K Smart TV has 8 other known error codes, including: 2 BLINKS (Power Supply Board Fault), 5 BLINKS (LED Backlight / Driver Protection Shutdown), 6 BLINKS (Main Board / T-CON Communication Failure), ANYNET FAIL (Anynet+ (HDMI-CEC) Not Working), APP CRASH (App Freezes or Crashes), and 3 more.

Error code MODE NOT SUPPORTED also appears on 4 other Samsung TV & Audio models: QN55LS03BAFXZA 55" Class The Frame QLED 4K Smart TV, QN65Q80CAFXZA 65" Class Q80C QLED 4K Smart TV, QN65S90CAFXZA 65" Class S90C OLED 4K Smart TV, UN55CU8000FXZA 55" Class CU8000 Crystal UHD 4K Smart TV. The fix may vary by model, so check each model's specific page for tailored repair steps.