Macpro running 3 external monitors

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piloadami Author

Level 1

15 points

Macpro running 3 external monitors

I'm looking to add a 3rd monitor to my set up. I'm currently running:

Macpro 5.1 early 2009 with an ATI Radeon HD 5870 1024 MB

1st monitor - Mindisplay port adaptor to HDMI into an ultrawide LG running SwitchResX4 for maximum resolution

2dn monitor - DVI out into DVI in a DELL monitor

There's another minidisplay port available so I've tried connecting an adaptor out into HDMI into a BENQ monitor with no avail, the macpro seems to only run 2 monitors at a time, is there a solution for this or would I have to purchase another graphics card?

I've also tried displayport adaptor out into HDMI and no success.

Many thanks

Mac Pro

Posted on Oct 24, 2020 1:35 PM

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Answer 1

Oct 24, 2020 4:38 PM in response to piloadami

Apple did publish a connection guide

Mac Pro (Early 2009), Mac Pro (Mid 2010), Mac Pro (Mid 2012): Supported display configurations - Apple Support

that seems to imply both adapters should be active when using three displays. They don't explicitly talk about active vs passive,

but their normal DVI adapter is passive, and the VGA and Dual-Link DVI adapters are active.

Do your HDMI displays also have DisplayPort? That is always preferred over HDMI and you can use Mini DisplayPort to DisplayPort cables, which don't count as adapters.

https://www.startech.com/en-us/cables/mdp2dpmm6

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Answer 2

Oct 24, 2020 4:32 PM in response to piloadami

You can use as many Displayport family as you like.

Running more than TWO "legacy" {DVI, HDMI, VGA} displays requires the third and subsequent must use ACTIVE adapters (the built-in Legacy ports each count as one if you connect anything to them.

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Answer 3

piloadami Author

Level 1

15 points

Oct 25, 2020 2:28 AM in response to Malcolm J. Rayfield

I might just buy one and see what happens!

The LG ultrawide screen has only 2 HDMI ports and the BENQ offers VGI but none have minidisplay.

I did tried and plug minidisplay port cable into displayport on the DELL (which is currently running with DVI) but that also didn't work.

Will get back with results!

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Answer 4

piloadami Author

Level 1

15 points

Oct 29, 2020 9:49 AM in response to piloadami

Update on this:

I've ordered an active HDMI from amazon https://www.amazon.co.uk/gp/product/B01GYAW3V8/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1

Unfortunately I can't get all 3 screens to work, I know the adapter works cause I can have both HDMI on minus the DVI, or DVI + HDMI (active or passive) but not all 3, after turning the 3rd screen with active HDMI on it all I get is 'no cable connected'

Not sure where to go from there, if anyone has any insights please let me know, I'm suspicious either my video graphics doesn't support 3 external screens or the adapter is not a 'legit' active one

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Answer 5

Oct 29, 2020 10:26 AM in response to piloadami

There have been sporadic reports of not supporting TWO "legacy"-interface displays. Malcom Rayfield also suggested that the Apple article on that subject is at least ambiguous, and does not say outright it supports two without ACTIVE adapters.

So if you cannot move to DisplayPort, use another ACTIVE adapter.

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