Guides

External display problems, answered

The answer first, with the numbers behind it, then the steps.

• 4K monitor stuck at 30 Hz on a Mac

  4K at 60 Hz needs about 12.54 Gbps. HDMI 1.4 carries 8.16 Gbps, so a hub or adapter with HDMI 1.4 forces 30 Hz. How to find the weak link and fix it.

• Blurry text on a 1440p monitor on a Mac

  A 27-inch 1440p monitor has about 109 pixels per inch. macOS draws sharpest at 2×, around 218 ppi, so 1440p text looks soft. Your options, from free to new monitor.

• M4 Mac: sharp 4K HiDPI mode missing

  On M4 and M5 Macs the HiDPI frame is limited to 6,720 pixels wide, so a 4K monitor can't get a sharp “looks like 3840×2160” mode. Why, and the virtual display workaround.

• External monitor flickering on macOS Tahoe

  Since macOS Tahoe 26, many people report external displays flickering or blanking for a moment. How to tell an OS problem from a cable or hub, and what to try.

• DisplayLink limits on a Mac

  DisplayLink lets a Mac drive more displays than it supports on its own, over USB. The trade-offs: compressed video, CPU use, no hardware brightness control.

• Use your MacBook Pro's HDR brightness for everything

  A MacBook Pro with a Liquid Retina XDR display keeps its brightest light for HDR video. How to use it for everything else, and what it costs in battery and heat.