I recently had an issue with my XFX R9 280X with MAC EFI and two brand new BenQ PD2700U monitors. The monitors connect via Thunderbolt cables (and you can plug a Thunderbolt cable in to Mini DisplayPort to get video output only).
Upon powering on the system and trying only one BenQ monitor, it was just a white screen.
Upon PRAM reset the system booted with a chime and then chimed every 2 seconds infinitely.
When I tried re-seating the ram, still the same issue persisted.
I unplugged the monitor cable from the mDP port in the R9 280X GPU. The system booted up normally and then I plugged in the cable, and there was perfect video output to the gorgeous new monitor!
I did a quick reboot, and had the infinite chime loop
I tried a backup Gigabyte Windforce Radeon R9 280X with its own Mac EFI... same issues as with the XFX R9 280X.
I swapped to an MSI Aero RX 460 4GB, and had zero issues!
Does anyone have an educated guess at to what the issue with the R9 cards is? mDP has no issue doing 4K, but it seems to not like this BenQ monitor.
Upon powering on the system and trying only one BenQ monitor, it was just a white screen.
Upon PRAM reset the system booted with a chime and then chimed every 2 seconds infinitely.
When I tried re-seating the ram, still the same issue persisted.
I unplugged the monitor cable from the mDP port in the R9 280X GPU. The system booted up normally and then I plugged in the cable, and there was perfect video output to the gorgeous new monitor!
I did a quick reboot, and had the infinite chime loop
I tried a backup Gigabyte Windforce Radeon R9 280X with its own Mac EFI... same issues as with the XFX R9 280X.
I swapped to an MSI Aero RX 460 4GB, and had zero issues!
Does anyone have an educated guess at to what the issue with the R9 cards is? mDP has no issue doing 4K, but it seems to not like this BenQ monitor.