Quick answer
For your first Monitor test, do not change many settings: allow permission, pick the right device and run the default test. Monitor testing covers dead pixels, uniformity, refresh rate and cable/port issues.
Why it matters
Change one variable at a time so you know what fixed it.
Dead pixels are easiest to spot on full-screen solid colors; windowed tests miss them.
Step by step
- Close apps that may lock the Monitor (meetings, streaming, recording, chat).
- Allow Monitor permission in the browser address bar and OS privacy settings.
- Select the exact Monitor in the device list instead of trusting 'system default'.
- Run one input/output test and watch 10-30 seconds for dropouts, clipping or stutter.
- Retest with another browser, port or cable to see whether the issue reproduces.
Common mistakes
- Testing the Monitor in one app only, without another browser/meeting app.
- Ignoring OS privacy settings while repeatedly clicking Allow on the page.
- Judging with a bad cable or unpowered hub and declaring the device dead.
- Mistaking software gain/beauty filters/noise suppression for hardware quality.
Checklist
- The Monitor is recognized by the OS.
- Browser and OS permissions are allowed.
- Input/output device selection is correct.
- A 30-second run has no dropouts.
- A second environment reproduces the same result.
Key facts
- Dead pixels are easiest to spot on full-screen solid colors; windowed tests miss them.
- A refresh rate cap is often cable/port/settings, not the panel.
FAQ
How do I start testing my Monitor?
For your first Monitor test, do not change many settings: allow permission, pick the right device and run the default test. Monitor testing covers dead pixels, uniformity, refresh rate and cable/port issues.
How long does it take?
Usually 1-3 minutes; for intermittent issues, run 30 seconds and retest elsewhere.
Is data uploaded?
Runs locally and does not upload video/audio; extensions may still read the page.
Source: MDN Screen