Used monitor checklist: tests before buying

Updated · 13.10.2026 · MonitorTest

Check the actual unit under controlled conditions: model, pixels, motion and connection. Record repeatable observations before buying.

Verify the unit and conditions

Ask to power on the actual unit, not a catalogue image. Check its model label, stand, casing, ports and supplied cables. Confirm the input needed for your setup; an HDMI or USB-C label alone does not establish compatibility. Ask about use and repairs, and mark unverified history as unknown.

Compare pixels and panel appearance

Select the native resolution and 100% browser zoom for patterns. Inspect black, white, red, green and blue in turn. Recheck a fixed point against a clean surface and different content. Look for broad patches or bands on grey and white. Compare corner glow from normal seating, at comfortable brightness and different angles; a dark phone photo alone is not proof of a fault.

Check the connection and motion

Confirm the intended resolution and refresh mode in the operating system; browser estimates are not physical panel measurements. For a display problem, try a direct connection without the dock, then a known-good cable. Compare two overdrive settings with the same moving pattern and speed. The highest setting may produce stronger inverse trails. Repeat with everyday games or video, and check sleep and wake.

Record findings and understand limits

If the symptom repeats, record model, input, resolution, Hz, brightness, room light and pattern. Keep an overall panel photo and a close-up together. If built-in diagnostics exist, follow your exact model’s manual; button sequences are not universal. A short browser check cannot certify every intermittent fault or colour accuracy. Verify return and warranty conditions with the seller for the exact product.