Previous 1 2 Next 15 Replies Latest reply: Feb 8, 2011 6:36 PM by Eric Strausser
Eric Strausser Level 1 (10 points)
I have a 2.8 Mac Pro mid 2010. The model identifier is MacPro5,1
I have the following monitors connected to it in order from Left to Right starting with the DVI port.

Sony SDM-HX73 connected to the DVI port on the 5770. (1280x1024)
Viewsonic VX2235wm connected with a Generic Mini Display to DVI. (1680x1050)
Both the above LCD Monitors have VGA ports as well. Those are connected to my old Power Mac G5.

Sony KDL40XBR6 TV connected with a Kanex Mini Display to HDMI. This connection carries picture and audio over an HDMI cable to my TV. Works great.

Here is my problem. I always have the Viewsonic plugged in. That's my main monitor. But I have to alternate between the two Mini Display ports depending on whether I want my second computer monitor, the Sony SDM_HX73, or whether I want to watch something on my TV. Usually I like to send Hulu or South Park Studios over to the TV.

Is there a way to tell the 5770 card to ignore one or the other Mini Display ports? Anyone seen a KVM for this kind of thing? Is there software that could do this? Basically, if I plug in the Mini Display port that's connected to the HDMI the Mini Display port that's connected to the DVI shuts off. I"m fine with one cancelling the other out, but hate that I have to get up and swap the plugs when I want to switch. Make me feel like a dinosaur. Any ideas?

Mac Pro 2.8Ghz 16Gig Ram, Mac OS X (10.6.6)
  • Alain Mikli Level 1 (0 points)
    I can explain why you only have 2 monitor up and why they will switch when you plug the 3rd one in.

    5770 can only output 2 monitors in the same time, if you want 3 monitors running at the same time, you have to use "Mini Display Port to Dual Link Adapter" instead of "Regular Mini Display to VGA/DVI Adapter".

    Hope this help.

    If 3 monitors running all together, so you can switch the signal on the monitor itself, would it solve your problem
  • X423424X Level 6 (14,215 points)
    I have a similar (but not exact) problem to yours. I have my main 27" ADC monitor connected to one of the mini displayports (mDP) on my 5870 video card. The other mDP is usually connected to a second monitor - a VGA through a mDP to VGA adapter. But I also want to be able to use my Sony 32XBR6 sometimes. That means, like you, getting up and unplugging the VGA and plugging in the mDP to HDMI adapter (which in turn is connected to my HDTV).

    I've done extensive google searches looking for what amounts to a mDP A/B switch (not a KVM -- apparently one mDP KVM I found cannot be run in reverse). So far it looks like such an animal doesn't exist.

    So I've resigned myself to having to physically change the plugs. But one concern I had with this is waring out the mDP socket on the video card. So what I am going to do is get a mDP extension cable (i.e., male-to-female), plug that into the video card, and then plug the TV or VGA into the extension cable. I think it's much better to ware out the socket in a cheap extension cable than the expensive video card. In addition it is also easier to switch the plugs at the end of a 3' cable than having to reach behind my mac pro and change the plugs there.
  • Eric Strausser Level 1 (10 points)
    Thanks for that, Alain. No matter what I do to the second desktop monitor, if the TV is plugged in it kills it. I tried shutting off the TV but no go. The only thing that brings back my second monitor is to pull the tv from the mini display port. That 100 bucks is kind of steep. Why would that make all three ports open up simultaneously when a single link cable doesn't?
  • Alain Mikli Level 1 (0 points)
    That's what I'm not sure too. But not only in Mac, in PC, if you want to have three ports open up simultaneously, you have to use something like "Active Display Port" the same stuff as mini display port to dual-link dvi which include an extra usb cable of the adapter. Might be running 3 monitors need some "extra data transfer", that's why we need this kind of stuff.

    But I do read from some other thread saying that, when you using VGA instead of DVI, you don't need such an adapter for "that VGA monitor". But I don't have a mini-display to VGA adapter to try if it really works.

    For example, if you have DVI*2, VGA*1 monitors, what you need is
    1st DVI - plug directly to DVI port
    2nd DVI - using mini display to dual link adapter
    3rd VGA - mini display to VGA adapter
  • Eric Strausser Level 1 (10 points)
    Hey Alain. Can you explain why this work? Have you seen what you described work? The 100 bucks for the mini display to dual link adapter is kind of slowing me down.
  • Grant Bennet-Alder Level 9 (56,531 points)
    Might be running 3 monitors need some "extra data transfer", that's why we need this kind of stuff \[adding USB].

    It's not the USB data that is needed to run three displays. It's the extra POWER. If you read the Apple article, they say the only solution they endorse is their US$100 Dual-Link adapters. Check the table at the end of the article.

    Mac Pro (Early 2009), Mac Pro (Mid 2010): Supported display configurations

    But readers here have found that if you have two Brand-X Powered adapters, aka active adapters, it also works fine. These do not always require another USB. If designed recently, they can pick up a power pin in the Mini DisplayPort interface.
  • Eric Strausser Level 1 (10 points)
    Hmmm. Thanks Grant. I'll look for that Brand-X Powered adapter before I drop the 100 bucks. Do you think that my mini to HDMI will need to powered as well? The cable I haven now is not powered. Guess I will find out.
  • Grant Bennet-Alder Level 9 (56,531 points)
    That article is a bit information dense without being especially enlightening. But the Note right above the table helps a little:

    Note: If you are using an Apple Mini DisplayPort to DVI adapter, only two displays are supported across the three ports. If you are connecting three displays, any DVI displays must be connected to either the Dual-Link DVI port or must use an Apple Mini DisplayPort to Dual-Link Adapter.

    So as I read it, you can use the regular DVI for free, but if you want an additional DVI off a Mini DisplayPort, you have to limit yourself to two displays or use the expensive Apple ACTIVE adapter to do the conversion. \[Or use a Brand-X ACTIVE adapter.]
  • JanosX Level 1 (0 points)
    If the adapters are $100 each, could you not just buy a second card and have up to 4 monitors with out the hassle... it would also cost you the same or less than 2 adapters.

    Also, referencing the article that grant linked too, can a MP 4,1 (early 2009) install and run 2 5770's? Each using one of the additional power connectors?

    Sorry, I'm trying to figure this all out in an evening as I take possession of my first Mac Pro tomorrow morning. It's an early 2009 that I want to do some quick upgrades too.
  • X423424X Level 6 (14,215 points)
    In addition to the Apple tech note mentioned earlier here's a related Apple tech note:
  • Eric Strausser Level 1 (10 points)
    So it's looking like buying the 100 dollar part from apple is the cheapest solution to have all three ports working at once. Though I have to admit that the technical articles confuse me. Just when I feel like I've been told something I realize that I still don't feel confidant as to what the solution really is. I'm going to put the mini display port to Dual link DVI on my biggest desktop monitor. The other desktop monitor will plug directly into the DVI port on the card and the 40 inch tv will still connect via HDMI over the second Mini Display port.
  • Grant Bennet-Alder Level 9 (56,531 points)
    This page at AMD (makers of the 5770 and 5870) lists the qualified POWERED adapters that meet their most stringent requirements. Look down the page and you will find several qualified Active Mini DisplyPort to various others, such as HDMI. These adapters are available from other outlets, such as Amazon, sometimes for far less than the Apple adapters.
  • Eric Strausser Level 1 (10 points)
    Sweet! I'll check that out. Thanks Grant.
  • Malcolm Rayfield Level 7 (28,075 points)
    I'm going to put the Mini DisplayPort to Dual link DVI on my biggest desktop monitor. The other desktop monitor will plug directly into the DVI port on the card and the 40 inch tv will still connect via HDMI over the second Mini Display port.

    That will work only if you use an active Mini DisplayPort to HDMI adapter. The only one I have found is:
    but you should confirm that they are really active before buying 500 of them.

    You can connect a DVI to HDMI adapter or cable to an active Mini DisplayPort to DVI adapter but that won't give you any audio over HDMI.

    You could connect the DVI displays to the Mini DisplayPorts with active adapters and use a DVI to HDMI cable or adapter from the DVI port to the TV.

    If you want audio via HDMI, you can use audio from the Mac Pro's optical output with this DVI to HDMI converter:
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