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I've recently acquired a new Mac Pro in work (the Late 2013 cylindrical model, running OS X 10.9.3) and am trying, unsuccessfully, to connect 3 identical DVI displays to it (running at 1280 x 1024 @ 60Hz).

I have followed the instructions in Mac Pro (Late 2013): Using multiple displays to the letter with no success. The article suggests I can indeed connect more than 2 DVI or HDMI displays to it.

Here's what I've tried so far:

Display 1 connected via HDMI to DVI adapter (into HDMI port)

Display 2 connected via (passive) Mini DisplayPort to DVI adapter into Thunderbolt port 1 (as in the diagram in the above article)

Display 3 connected via (passive) Mini DisplayPort to DVI adapter into Thunderbolt port 2.

Only 2 of the monitors became active, as expected, as the article also says that only 2 displays can be used with passive adapters in the "Can I connect a DVI display?" section

Given this, I obtained some Apple Mini DisplayPort to Dual-Link DVI adapters, which the article suggests are required for connecting more than 2 displays and connected them using only one of the active Mini DisplayPort to Dual-Link DVI adapters as follows:

Display 1 connected via HDMI to DVI adapter (into HDMI port)

Display 2 connected via (passive) Mini DisplayPort to DVI adapter into Thunderbolt port 1 (as in the diagram in the above article)

Display 3 connected via (active) Mini DisplayPort to Dual-Link DVI adapter into Thunderbolt port 2 (and its USB cable into one of the USB ports).

Still only 2 displays are active. I then tried all three (active) Mini DisplayPort to Dual-Link DVI adapters together (with the USB cable for each also plugged into a USB port) as follows:

Display 1 connected via (active) Mini DisplayPort to Dual-Link DVI adapter into Thunderbolt port 6 (as in the diagram in the above article)

Display 2 connected via (active) Mini DisplayPort to Dual-Link DVI adapter into Thunderbolt port 1

Display 3 connected via (active) Mini DisplayPort to Dual-Link DVI adapter into Thunderbolt port 2

Still only 2 displays are active. I then tried various combinations of all the above using different Thunderbolt and USB ports (respecting the Thunderbolt bus arrangement in the article) and different combinations of active and passive DVI adapters. Nothing seems to give me more than two displays.

All of the displays are fine as I've checked them individually and I've noticed that when I have 3 displays plugged in (one always inactive), if I unplug one of the active ones, the remaining inactive one will spring into life.

Hopefully someone can point out what I'm doing wrong. Or is there an issue with the current software or firmware that prevents this from working?

  • How were you able to run that last test with ALL 3 displays on Mini DisplayPort to Dual-Link DVI adapters (Active) when your previous tests consisted of 1 with DVI, the other two on Mini DisplayPorts? Just curious because I have a tower model (just before the cylinder came out) with a similar card that only handles 1 DVI + 2 Mini DisplayPorts (thunderbolt). Worst part is, my setup used to work, but up until recently it's like it just "chose" to break (didn't move/change any connections, viva la technology...) – bigp Jul 13 '14 at 17:20
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After more playing around, I now have a workaround whereby using a Mini DisplayPort to VGA adapter instead of one of the Mini DisplayPort to DVI adapters, i.e. an analogue connection to one of the displays instead of digital, seems to work and allows me to have 3 active displays configured like so:

Display 1 connected via HDMI to DVI adapter (into HDMI port)

Display 2 connected via (passive) Mini DisplayPort to DVI adapter into Thunderbolt port 5 (as in the diagram in the above article)

Display 3 connected via Mini DisplayPort to VGA adapter into Thunderbolt port 2.

However, I was hoping to have an all-digital solution as the above Apple article suggests I can, so I'm still hoping someone will come up with a better idea!


UPDATE: This appears to be an issue introduced with OS X 10.9.3. Tried an identical machine running 10.9.2 and the second configuration I tried in the original question worked just fine. Hopefully it'll be fixed in 10.9.4, until then the workaround above is still valid.

  • Just not to mislead people, there is no such thing as a "DP to VGA passive adapters". ALL DP to VGA adapters are ACTIVE. It is impossible to just rewire a DP signal into an analog signal. Note: many many people have had problems with cheap no-name brand adapters. Make sure to buy only 4 stars & more adapters from Amazon (Startech are very good ones) and only buy active ones. Note 2: to connect up to 4 legacy monitors, you may also use an MST hub. – Joel Sep 20 '14 at 2:19

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