Apple Silicon M4 and M5 processors now restrict HiDPI 4K external display scaling to 3360x1890 (1.75x native resolution), down from M2/M3 capabilities. Users face a choice between blurry 4K (3840x2160) or smaller sharp text at 3.3K. Technical analysis confirms this isn't hardware-limited - both M2 Max and M5 Max report identical display capabilities via DCP, but the M5's GPU driver (AppleDisplayCrossbar) caps framebuffer allocation at 1.75x scaling instead of full 2.0x.

Testing shows EDID patches, registry overrides, and private APIs fail to bypass this enforcement, suggesting firmware-level restrictions. The M5 Max's 8K support (7680x4320) remains untapped due to this conservative resource allocation strategy.