My MacBook Pro M5 running MacOS Tahoe 26.3 beta fails to detect two identical ASUS ROG Swift OLED PG32UCDM monitors simultaneously. Only one display is recognized at a time. One potential root cause might be that both monitors report identical binary EDID serial numbers (0x01010101), and the MacBook Pro M5 appears to use this value exclusively for display identity rather than combining it with other more detailed information (e.g., port, or alphanumeric serial number). I've verified that the monitor EDID binary serial numbers are in fact identical -- however the alphanumerical serial numbers are not identical. NOTE: This behavior is specific to the MacBook Pro M5 — when connecting both monitors via usb-c to a Mac Mini M4 Pro running the same MacOS Tahoe 26.3 beta, the monitors work fine. The OS detects both and assigns different names to them (PG32UCDM (1) and PG32UCDM (2)). NOTE: I could be wrong about this root cause, I don't have a way to disprove it, though the fact the monitors work fine on a Mac Mini is
Topic:
App & System Services
SubTopic:
Hardware