Chosen Solution
I recently was given a used Apple Cinema HD Display (with original PSU), however I am unable to obtain a full-resolution output (2560x1600) from my Function Keys MBP to the display. I am only able to achieve 1280x800 resolution after purchasing a recommended Club3D USB-C to Dual Link DVI adapter (CAC-1510) which has reviews stating it is fit for purpose and has documentation on its product page suggesting it would work. I am running on the latest version of macOS Catalina (10.15.4). I believe the adapter does work as when connected to a Lenovo Thinkpad t480s over both of its USB-C ports, the display functions at full resolution (2560x1600) with no issues. I’ve tried fixes posted elsewhere online in the following order: Holding the option key to display additional scaled resolutions once clicking the ‘scaled’ button;Resetting SMC / NVRAM / PRAM / anything else that can be reset from those guides;Disassembled and inspected the USB-C connectors, given a clean and reassemble my MacBook Pro;Installed a clean version of High Sierra to ensure it isn’t a software problem (with the same result, now installed back to 10.15.4 using a time machine backup);Deleted a display .kext file from Library/Preferences/ and rebooted the machine to no avail;Used the options modifier key for the display scaling in safe mode and switched back to normal boot. If anyone has any guidance on what else I could do, please let me know. I’m at a loss and would just like the monitor/adapter to function as advertised with my MacBook Pro ASWELL as my Thinkpad! I am unaware of any hardware restrictions but if this is the case then apologies for the long wall of text. Thanks in advance!
I think the issue is within your MacBook Pro’s ability to handle the dual DVI interface. The issue is the way dual DVI works and what Apple tested during the development of your system. Given the age of the Cinema Display’s (EOL back in 2010 + 4 would still be vintage) I think Apple only went back to 27” Thunderbolt display. Technically, Apple’s interface is Thunderbolt 3 not USB-C so that could be a factor here. Yes, the connectors are the same but the USB-C interface is still different! Other USB-C devices have been found not to work. I would talk with the maker of the Club3D USB-C to Dual Link DVI adapter (CAC-1510) maybe they know of something.
