Display and screen tests
Three ways to interrogate a panel — a full-screen colour field for pixel faults, a measured refresh rate in Hz, and a live frame counter while something is moving.
Dead pixels, stuck pixels and how to tell them apart
Fill the screen with a solid colour and faults become impossible to miss. Cycle through white, black, red, green and blue, and look closely — a dead pixel stays black on every colour, because the transistor behind it has failed. A stuck pixel does the opposite: it is bright and fixed on one colour, and it stands out most against black.
The distinction matters because stuck pixels sometimes recover. Manufacturers usually treat a handful of dead pixels as within spec, so check the warranty threshold before starting a return. Take the test in a dim room; a reflection off a lit window hides exactly the kind of single-pixel fault you are hunting for.
While you are on a white field, it is also the easiest time to spot dust under the glass and any uneven backlight bleed along the edges.
What refresh rate and FPS actually tell you
Refresh rate is how many times per second your panel redraws, measured in Hz. Buying a 144 Hz monitor does not mean you are running at 144 Hz — Windows and macOS both frequently default a new display to 60 Hz, and a cable or port that cannot carry the bandwidth will quietly cap you there too. A quick monitor test in the browser is the fastest way to catch that, and the fix is usually one setting away in display preferences.
The frame counter is a different measurement. It reports how many frames the browser is managing to paint per second, which is a reasonable read on whether animation feels smooth and whether the page is being hardware accelerated at all. It is a browser measurement, so it is not a substitute for an in-game benchmark — a game bypasses the browser entirely.
One thing to expect: on a variable-refresh display with FreeSync or G-Sync active, the measured rate moves around by design. A number that drifts is the panel doing its job, not a fault.
Before you blame the panel
Reseat the cable and try a different port first. Flicker, dropouts and a rate stuck at 60 Hz are more often a marginal cable or an adapter than a failing screen, and swapping one is free.