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User profile for user: rtclark2
rtclark2 Author
User level: Level 1
8 points

MacPro (late 2013) running Catalina only detecting two of four displays.

Hello good samaritans i am hoping someone can help me with a problem.


I have MacPro (late 2013) running Catalina and i am trying to connect four monitors to it but can never get it to detect more then two


I am using VS278Q Full HD LED monitor 27"monitors with each monitor connected by aMini DisplayPort to HDMI Display Adapter Cableto one of the TB2.


Here is a link to a mark up of what TB2 ports the monitors are hooked up to.


I have tried moving the cables to different ports, but that just changes what monitors are active.


I have tried a PRAM/NVRAM reset but that dosnt help.


When i run system report both AMD FirePro D300 chips show up but only one shows that it has displays attached (two) the other shows none.


Any help with is is appreciated

Mac Pro, macOS 10.15

Posted on Nov 12, 2019 7:30 PM

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User profile for user: Malcolm J. Rayfield
Malcolm J. Rayfield
User level: Level 7
23,059 points

Posted on Nov 12, 2019 10:07 PM

All displays are driven by just one of the graphics cards. The other is for computation only.


Use multiple displays with your Mac Pro (Late 2013) - Apple Support


Your problem is that the adapter cables are passive, not active. The 2013 Mac Pro can not handle more than two passive adapters. The built-in HDMI port counts as one, if it is used.


Since your displays have DisplayPort, just use Mini DisplayPort to DisplayPort cables. The Mac Pro Thunderbolt ports work with Mini DisplayPort cables.

https://www.startech.com/Cables/Audio-Video/DisplayPort/6-ft-Mini-DisplayPort-to-DisplayPort-Adapter-Cable-Male-to-Male~MDP2DPMM6

These don't count as adapters since they don't change the signals, just the connector.

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User profile for user: Malcolm J. Rayfield
Malcolm J. Rayfield
User level: Level 7
23,059 points

Nov 12, 2019 10:07 PM in response to rtclark2

All displays are driven by just one of the graphics cards. The other is for computation only.


Use multiple displays with your Mac Pro (Late 2013) - Apple Support


Your problem is that the adapter cables are passive, not active. The 2013 Mac Pro can not handle more than two passive adapters. The built-in HDMI port counts as one, if it is used.


Since your displays have DisplayPort, just use Mini DisplayPort to DisplayPort cables. The Mac Pro Thunderbolt ports work with Mini DisplayPort cables.

https://www.startech.com/Cables/Audio-Video/DisplayPort/6-ft-Mini-DisplayPort-to-DisplayPort-Adapter-Cable-Male-to-Male~MDP2DPMM6

These don't count as adapters since they don't change the signals, just the connector.

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MacPro (late 2013) running Catalina only detecting two of four displays.

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