how do I connect 2 thunderbolt & 1 HDMI monitors

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Level 1

40 points

how do I connect 2 thunderbolt & 1 HDMI monitors

I'm trying to connect an HDMI video monitor as well as my two normal thunderbolt monitors to my MacPro 2013, but only two out of the three monitors are showing any signal (if I disconnect one of the Thunderbolt monitors then the HDMI monitor will start to work).

My Mac Pro (2013 8 core) has two AMD FirePro D700 graphics cards.

I want to use my HDMI monitor purely as a video monitor for video editing

thanks in advance for your help!

Mac Pro, OS X El Capitan (10.11.4), MP 2013, 3 GHz 8-Core Intel Xeon E5

Posted on Apr 25, 2016 10:22 PM

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Answer 1

Best reply

Malcolm J. Rayfield

Level 7

22,963 points

Apr 26, 2016 12:30 AM in response to ZillaB

Make sure you don't have all the displays on the same Thunderbolt bus.

https://support.apple.com/HT202801

"This means that if you use the HDMI port, be sure to then only use one of the bottom two Thunderbolt ports (Bus 0)."

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Answer 2

ZillaB Author

Level 1

40 points

Apr 26, 2016 12:32 AM in response to Malcolm J. Rayfield

Thanks Malcolm,

I think this will solve my problem - but I'll have to buy another connector; my two main displays are DVI monitors, connected by DVI to Thunderbolt convertors, and I'll need to buy an active DVI adapter and use that as well.

Thanks for your advice though, it's been very useful!

Cheers

Andrew

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Answer 3

lllaass

Level 10

210,417 points

Apr 26, 2016 1:05 AM in response to ZillaB

I was mislead when you originally said Thunderbolt monitors. You do not have thunderbolt monitors, you have two monitors with DVI input and one with HDMI input.

Your Mac can only connect to two monitors with legacy connector (HDMI and DVI) using the cheap non-active adopters for more than two legacy connections, the third and more adopter have to be active adopters.

I would purchase one active mini displayport>DVI adopter like this one

https://www.startech.com/AV/Displayport-Converters/Mini-DisplayPort-to-DVI-Activ e-Adapter~MDP2DVIS

The connect the HDMI monitor to the HDMI port and connect the other two monitors by one not active adopter and one active adopter. Make sure each is connected to a different Thunderbolt bus.

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Answer 4

ZillaB Author

Level 1

40 points

Apr 26, 2016 5:46 AM in response to lllaass

Thanks Illas, you're quite right - I'd forgotten that my monitors are actually DVI, not Thunderbolt! Yes, I have to buy an active convertor like the one you've suggested.

Cheers

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Answer 5

Apr 26, 2016 8:15 AM in response to ZillaB

ACTIVE adapters cost about US$40, and are sold as ACTIVE to justify their higher cost. They contain signal re-driver circuits, which boost the low DisplayPort-level signals up to "legacy" display levels.

If your DVI displays are not wider than 1920, you can use Single-Link ACTIVE adapters. If over about 1920 wide you need the VERY expensive Dual-Link DVI adapter.

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Answer 6

ZillaB Author

Level 1

40 points

Apr 26, 2016 4:20 PM in response to Grant Bennet-Alder

Thanks Grant, I was trying to find an answer to the difference between the cheaper single link ACTIVE adapters and the more expensive Dual Link DVI adapter.

My DVI monitors are 1920 x 1200, so fortunately I can use a single link Active adapter.

Thanks for clearing this up!

Cheers

Andrew

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Answer 7

Apr 26, 2016 7:02 PM in response to ZillaB

The ACTIVE Dual-Link adapter has an additional set of 3 push-pull Driver circuits inside, and splits the color data across the two sets of three, because otherwise the clock rate on that data would get completely out of hand. because it has so much electronics inside, it needs a USB pigtail to pick up more power to run all the electronics.

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