New Apple Silicon M4 & M5 HiDPI Limitation on 4K External Displays
Summary
The article analyzes a regression in HiDPI support for external 4K displays on Apple Silicon M4/M5 Macs, reducing HiDPI backing store to 3360x1890 and leaving users with either blurry 4K or a smaller HiDPI workspace. It provides extensive diagnostic steps, comparing M2 and M5 behavior and identifying the GPU driver’s mode-generation policy as the limiting factor rather than hardware. The piece also discusses potential fixes and user actions, including feedback to Apple and community tools like BetterDisplay.