KVL for sharing monitor with two Mac Pro desktops

Question

KVL for sharing monitor with two Mac Pro desktops

I have two Mac Pro desktop computers.

1. Mac Pro 5.1 (the aluminum tower setup).

2. Mac Pro ‘trashcan’. Little round black one.

I am using the Apple adapter that works with the Cinema Display (works fine hooked up directly)

Monitor: Apple 30” Cinema Display. DVI

the older Mac Pro has a Sapphire HD 7950 display card. It has DVI, mini Display Port and HDMI

The newer MacPro had HDMI and the Thunderbolt ports, which I understand can use a regular mini display cable/monitor.

I bought a

IOGEAR 2-Port Dual-Link DVI Cable KVM with Audio, GCS982U

But it doesn’t function correctly with this setup.

Any ideas of what I could use so I can share the 30” display with both computers? I use both for different things (the newer Mac Pro is dedicated just for ProTools). Moving the connections is a pain. Remote desktop works, but is slower and I loose screen room.

Mark

Mac Pro (Early 2009), OS X Mavericks (10.9), 14 gig RAM- 30" Cinema Display

Posted on Oct 16, 2018 4:44 PM

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Answer 1

Top-ranking reply

John Lockwood

Level 6

13,697 points

Oct 30, 2018 6:52 AM in response to Mark Hollingsworth

As far as I can see this KVM should be suitable for this requirement. It does say it is a 'Dual Link' compatible switch which is required to support the resolution of your 30" Cinema Display.

What you also need for the newer Mac Pro is a Displayport Dual Link Adapter, a 'standard' cheaper Displayport to DVI adapter does not support Dual Link and hence does not support the resolution required.

See - Amazon.com: Mini DisplayPort to Dual-Link DVI Adapter: Computers & Accessories

Since this iOGear KVM has built-in DVI cables you plug those in to the older Mac Pro video card DVI socket and in to the socket on the Apple Dual Link adapter for the newer Mac Pro.

The built-in cable from the Cinema display should then go to the DVI socket on the KVM.

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Answer 2

Oct 30, 2018 8:57 AM in response to Mark Hollingsworth

There is more complication:

To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, no data will be sent to the display.

This query is only sent at certain times:

• at startup

• at wake from sleep

• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go

• on invoking Option-(Detect Display) button in Displays preferences

So when the switch is set to the "other" computer at startup, the Mac will not be able to see it's response to the query, and that display will remain dark unless/until you do one of the suggested operations listed above.

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Answer 3

Oct 30, 2018 8:57 AM in response to John Lockwood

Yes, that is what I have. Neither the older Mac Pro connected directly or the newer one connected via the adapter you showed worked right at all.

I gave up and bought a Samsung 34” curved display with Thunderbolt.

I have the older Mac Pro connected via the HDMI port on my updated card and the HDMI port on the monitor.

the newer Mac Pro is connected via a thunderbolt port to the Display port via an inexpensive adapter.

The monitor uses Thunderbolt 3 and the Mac Pro of course has Thunderbolt 2. I could not find an adapter that appeared it would work, and the Display Port one was super cheap and I figured it was worth a shot.

it works perfectly.

Now I just swap the input on the monitor.

I do have to swap keyboards, but I have a Bluetooth one on the newer Mac Pro and already used two ‘Magic Mouse’ for each machine. So pretty easy.

the KVM would have been nice. But I wasn’t having any luck and the support from IOGear was awful. Plus the 30” Apple Cinema display is getting pretty old, although it still worked great. Guess I should try and sell that since I don’t have anything else I really need it for. I could use it as a second monitor- and if I have a big ProTools project may do that. But it takes a lot of room and I have limited space.

I certianly appreciate the input.

mark

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Answer 4

Oct 30, 2018 8:58 AM in response to Grant Bennet-Alder

thanks! Great info.

The KVM I bought was supposed to emulate the monitor I think- tricking the computer into thinking there was always a monitor connected. When I switched it would go to the new monitor fine- just unusable display.

thanks again

Mark

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KVL for sharing monitor with two Mac Pro desktops

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