Cable and port
Use the highest capability port and cable available. Check the monitor manual for which ports support the advertised mode.
Resolution and scaling
Set the native resolution. Adjust scaling for readability only after confirming the display mode is correct.
Refresh rate and HDR
Set refresh rate and HDR explicitly. Do not assume the operating system selected the best mode.
Run Pixy twice
Run Pixy before and after setup changes. Save both results if you need to compare.