Why won't my monitor run 4K 120Hz, HDR, 10-bit or full RGB?

How it works

You pick what you want. Display Detective follows the whole chain and marks the part that says no.

• Seven goals, one verdict eachNative resolution, highest refresh rate, 10-bit colour, full RGB, HDR, adaptive sync and sharp text. Each one is Achieved, Available or Blocked, with the numbers behind it.
• Measured, declared or calculatedEvery claim says where it comes from. When macOS does not report a fact, the answer is labelled as calculated, never passed off as measured.
• Plain answer firstOne sentence such as "Your Mac's HDMI port stops at 4K 60Hz", then the numbers, then the fix.

A Troubleshoot tab for every monitor

When the picture is wrong and the cause is not obvious, open the Troubleshoot tab of that monitor. Every reset the app knows is listed there, gentle ones first, in four groups.

• Quick fixesGentle changes such as the best mode macOS offers or a sharper scaled mode. Nothing on the screen is lost.
• ResetsThe picture is sent again or the mode changes for a moment, for example retraining the link. The screen goes dark for a second or two.
• By handSteps you do yourself, such as replugging both ends of the cable or trying another port, with a checklist to tick off.
• Danger zoneStrong changes. Each one asks once more before it runs.

When the diagnosis does not ask for a reset, the app can still try it. The button then says Run anyway. It runs through the same safety net as every other change.

Fix it safely

When the fix is a setting on your Mac, Display Detective can apply it for you.

• 15 seconds to keep or revertEvery change starts as a trial. If your screen goes black or you do nothing, it goes back by itself after 15 seconds.
• Cheapest fix firstA setting, then a monitor menu option, then a different port, then a cable or adapter, with the exact spec to look for.
• Hard limits stated plainlyIf your Mac or monitor cannot do it, the app says so and does not suggest a purchase that would not help.

Your AI assistant can drive it too

Everything the app does is also available without the window, through the same engine and with the same facts.

• Command lineA JSON tool, display-detective-check, lists displays, diagnoses them and shows fixes. A fix is a dry run until you add --apply.
• MCP serverRun display-detective-check mcp and connect it to Claude, Cursor or any MCP client. Applying a change needs an explicit confirm.
• Shortcuts and SiriActions to diagnose your displays, get a verdict for one display and apply the best setting. The last one asks before it changes anything.
• The same safety netApplied changes are session-only and revert after 15 seconds unless they are kept. The only connected display is protected.

Private by design

The app has no network access at all, no account, no telemetry and no analytics.

• No networkThe signed app does not ask macOS for network access, so it could not phone home even if it tried.
• On-device AIThe plain-language explanation runs on Apple Intelligence on your Mac when it is available. It only rewords facts the app has already measured.
• Feedback you controlThe feedback button copies a redacted report to your clipboard and opens this site. You read it and decide what to send. Serial numbers, UUIDs and your Mac's name are removed first.

Read the privacy policy

Requirements

macOS

26 (Tahoe) or later

Mac

Apple Silicon (M-series). Intel Macs are not supported.

AI explanation

Needs Apple Intelligence turned on in System Settings. Without it the app shows the facts and the verdict as before.

Permissions

Reads display and port state. No files, no network, no camera, no microphone.

Get Display Detective

Display Detective will be on the Mac App Store. This page gets the download button the day it goes live.

Does it work with HDMI, DisplayPort and Thunderbolt monitors?

Yes. It reads what macOS reports for each connected display, whichever port it uses.

Does it change my settings without asking?

No. It only reads until you press Run, and every change comes with a 15 second revert.

Does it work on Intel Macs?

No. Apple Silicon only.