LED Cinema Display to T3/USB-C ports

Discussion in 'Mac Pro' started by Xenious, Nov 4, 2016.

  1. Xenious macrumors 6502a

    Joined:
    Mar 22, 2004
    Location:
    Texas, USA
    #1
    I'm still hanging on to hope for a new Mac Pro. What I am now sorting out is the best way to ensure my LED Cinema Display has life because I really do love it a lot. I believe the solution is to use a USB-C to DisplayPort 1.2 cable (http://www.monoprice.com/product?p_...&utm_medium=11051853&utm_term=VigLink-2470763 - like this one) then a Displayport to MiniDisplayport adapter.

    Is my logic sound? I want to avoid the USB-C digital AV adapter from apple (passing through HDMI) because of the low refresh rate at higher resolutions.
     
  2. rawweb, Nov 4, 2016
    Last edited: Nov 5, 2016

    rawweb macrumors 6502a

    rawweb

    Joined:
    Aug 7, 2015
  3. deconstruct60, Nov 4, 2016
    Last edited: Nov 4, 2016

    deconstruct60 macrumors 604

    Joined:
    Mar 10, 2009
    #3
    Wait to see what a new Mac Pro has. I seriously doubt the new one will have to be a Thunderbolt v3 only port design. That would be kind of dumb. Apple has done dumb stuff before but that would be a new low.

    The current Mac Pro has an HDMI port. So Thunderbolt was not the one and only video out port in the current design. The next Mac Pro doesn't have to make Thunderbolt the one and only video out type port any more than the last design did. If there was just 4 TB v3 ports then there would be more than plenty room for:
    one mini-DisplayPort v1.2 ( v1.3)
    and one HDMI v2 port.

    That would make hooking the new Mac Pro "insanely great" easier in connecting to 3rd party displays than going obsessive compulsive disorder (OCD) on TB v3 only video out ports. Most 3rd party displays have one or both of these.

    As your use case points out there are plenty of folks who have DisplayPort (DP) devices hooked up to the Mac Pro now. Keeping just one mini-DP port probably covers a very significant fraction of users. Keeping the HDMI port even more so in the general 3rd party monitor market. Apple may throw the dual cable 5K display folks 'under the dongle bus" as they probably never liked that solution in the first place (and will push folks into their one-cable-does-it-all LG display). However, for 4K (and down)... there is no good rational to rock the boat for single display users.


    P.S. Same thing with stripping out all of the USB Type-A ports. Just plain beyond goofy. There is no "2-3 mm" height savings to be gotten. Ditto for the Ethernet port. The 3 prong power socket ( if they strip that off just haul the design team off to the insane asylum. No way the Mac Pro is going to fit inside of TB power limits. )
     
  4. Xenious thread starter macrumors 6502a

    Joined:
    Mar 22, 2004
    Location:
    Texas, USA
    #4
    Yea I was assuming that any new Mac Pro would be all T3 only and match the technology in the new Macbook Pro. I had also assumed that T3 to T2 adapter would be my answer but in this knowledge article on apple (https://support.apple.com/en-us/HT207266) it says that does not work of the apple display port devices. I read about going HDMI but that limits the refresh rate at higher resolutions so the best answer seems to be display port over USB-C.

    I recall someone found a reference to a potential Mac Pro with 8 or 10 T3 ports but I can't recall where it was....
     
  5. rawweb, Nov 5, 2016
    Last edited: Nov 5, 2016

    rawweb macrumors 6502a

    rawweb

    Joined:
    Aug 7, 2015
    #5
    Should work just fine. This from the support article you linked...
    "For example, you can use this adapter to connect your MacBook Pro to an Apple Thunderbolt Display or a third-party Thunderbolt 2 storage device."

    EDIT: I assumed the Apple thunderbolt adapter would "just work" and pass the displayport signal as it historically did with version 1 and 2. I was, incorrect. @deconstruct60 is correct below...

    What a head splitter...this TB3/USB-C is really wacky in some respects.
     
  6. deconstruct60, Nov 5, 2016
    Last edited: Nov 5, 2016

    deconstruct60 macrumors 604

    Joined:
    Mar 10, 2009
    #6
    The LED Cinema Display is not a Thunderbolt device. (It hails from 2010 or 2008 which predate Thunderbolt) It is a USB 2.0 and mini DisplayPort device. So this section is very much in play:

    " ...
    The Thunderbolt 3 (USB-C) to Thunderbolt 2 Adapter doesn't support connections to these devices:

    • Apple DisplayPort display ... "
    It is an Apple DP display.

    The technical hiccup is that the "Alternative mode" control mechanism of Type C ports is based on USB 2.0. So it is a somewhat different mechanism to do the legacy DP pass-thru handshake require to get the Type-C port to simply just pass through the native DP signals across the wires. TB v1-2 used a mini-DP port and just handled that legacy handshake themselves so it was much easier to just plug in a normal DP cable and get a response. Type-C requires more overhead.
     
  7. rawweb macrumors 6502a

    rawweb

    Joined:
    Aug 7, 2015
    #7
    Wow, did not see that in the article. That is complete baloney. My apologies to OP, it seemed like a no brainer. One more reason for me to stay with my late 2015 iMac...
     
  8. deconstruct60 macrumors 604

    Joined:
    Mar 10, 2009
    #8
    The MBP is making compromises to GPU and/or TBv3 bandwidth to get to 4 ports. Not sure why the Mac Pro should make compromises just to populate more TBv3 ports on the edge. Previous versions of MP had 400 and 800 FW ports during the transition to FW 800. This next Mac Pro is also a transitionary system. The MBP is so thin that it drives Type-C. For the Mac Pro everything Type-C has no such motivator. Type-C cannot cover the power for this system. So if have room for a three prong power connector this whole "have to save vertical space" is a bunch of hooey.

    Part of the driver fro the MP 2013 to have 6 TB ports was the presence of a fairly high number of legacy mode DP devices that were likely to be hooked up. You need 6 TB mDP ports if going to "blow" 2-3 of them on monitors. That way have 4-3 left to actually do TB specific work. If only have 4 TB v3 port blowing 2-3 of those on pure legcacy DP work is highly limitiing. (e.g., a MBP 2015 with two TP ports covered to drive a 5K monitor leaves you with no high bandwidth I;O left for externals. )

    There is still going to be be a large number of mDP/DP devices for desktops even if Type-C moves in. Same market forces that drove having the HDMI port on the MP 2013 are even bigger now than then ( many 10's of millions more monitors with HDMI on them.) Apple themselves drove substantive increase in 4K monitor sales with the MP 2013.


    [/quote]
    I read about going HDMI but that limits the refresh rate at higher resolutions so the best answer seems to be display port over USB-C. [/quote]

    Yes, getting the raw legacy DP signal out is best. That Apple does not have a Type-C to mDP adapter is quite off if their intention is to throw all DP display owners under the bus. Maybe they are still working on it.


    4-5 TBv3 controllers in a single machine is drinking a whole lot of kool-aid. Three is a bit contrived when there was mDP overlap. With pragmatically no display's with Type-C overlap it is mostly contrived. Besides, the next Mac Pro isn't going to have that kind of bandwidth. At least if they keep the 2nd GPU. Dumping the compute GPU just to have uniformity for uniformity sake of the external ports is goofy. Pushing the MP's compute GPU capability out onto a slightly less than x4 PCI-e v3 external connection isn't going to be make it more generally competitive.

    The more TBv3 port pairs you have while keeping the GPU constant starts to create problems in keeping up with the number potential screens you need to drive.

    5 is too many. If they do blow away x16 consuming compute GPU then 4 would be trackable. You are still down ports ( 8 TBv3 versus 10 ( 6 TB and 4 USB0 from the MP 2013 for no good reason what so ever.
     
  9. deconstruct60 macrumors 604

    Joined:
    Mar 10, 2009
    #9
    There might be some additional cost hackery Apple could have added on top to handle the edge case but likely would make the device much more expensive. Pretty sure Apple's adpater is using some low cost chip that Intel came up with to enable lower cost TB2-to-TB3 adapters. All it does is TB data to TB data only. ( that makes it simpler and more affordable.)


    Not so much baloney as part of the Faustian bargain of getting into bed with USB to use Type-C as an alternative mode. if a low cost adapter to downshift/upside TBv3 into/from TBv2 then that is all it does. (the other alternative and/or legacy modes are out on their own. )

    There should be purely dedicated DP only adapters too. They'll handle 2 or all 4 DP lanes and pretty much nothing else.

    These alternative modes don't really do what Thunderbolt does best. That is multiplex multiple protocols out to a remote/external device. A dock which does DPv1.2 and something else is a better fit. These individualized on narrow use adapters are a not so great use of TB ports.
     

Share This Page