Best 4k monitor cable?

Discussion in 'MacBook Pro' started by joejoejoe, Dec 29, 2016.

  1. joejoejoe macrumors 65816

    Sep 13, 2006
    Hey all,

    I'm having serious issues with my 13' TB MBP and connecting to my Asus 4k display.

    I've tried 2 different Display Port to USB 3 cables and the monitor rarely connects or holds a connection. I get serious flickering and a couple times the computer crashed and forced a restart. This is on both a Cable Matters cable from Amazon, and a direct cable from Google.

    Are other people having these issues?

    Is there a cable out there that works consistently and well?

    Could the issue be my computer in which case I need to go to the genius bar?

    Thank you
    --- Post Merged, Dec 29, 2016 ---

    This monitor works flawlessly with my previous MBP via a Display Port to Mini Display Port cable. Never had a single issue, so I don't think the monitor is the problem.
  2. WickedPorter macrumors regular


    Sep 28, 2012
  3. bartvk macrumors 6502


    Dec 29, 2016
    The Netherlands
    Well, if you tried two cables then I guess that rules out the cables. And the display worked before. So chances are high that it's the machine itself.

    And like Wicked said, StarTech makes good cables. If you want something cheaper and can wait, I like this cable:

    As an aside, my Samsung 4K monitor is sometimes wonky as well, when hooking up via USB-C -- I have to try a second or third time. And connecting in clamshell mode usually doesn't work at all, so I have the habit of opening the lid, connecting the 4K, then closing the lid.
  4. Gabrielanicolao macrumors member


    Dec 13, 2016
  5. Creep89 macrumors 6502

    Mar 9, 2012
    I use the StarTech cable and can confirm it just works. No problems at all connecting my rMBP to a Dell P2715Q. Gives me 4k@60hz.
  6. campyguy macrumors 68040

    Mar 21, 2014
    Portland / Seattle
    CableMatters doesn't make DP cables that are certified by - I've ordered and tested several DP cables from that company - all of them returned power over Pin 20, and none of them properly conveyed EDID info between the GPU and the display. IMO they're junk, and they've been binned.

    Google's cable returns power over Pin 20 and it's manufacturer also does not make DP-certified cables. IMO they're junk.

    Both Accell and StarTech make DP-certified cables, but none of their USB-C cables have been certified by yet. I've tested the new USB-C>DP cable and it does not return power over Pin 20, and I have the installed on two of my PC workstations connected to BenQ 4k displays.

    The second item to look for is throughput - the Accell cable and two StarTech cables are listed as 2160p (UHD) capable, which is what I look for in a video adapter cable that I'm connecting to a 4k display.
  7. joejoejoe thread starter macrumors 65816

    Sep 13, 2006
    thanks, could you clarify what power of pin 20 means? what does it do, and is it good or bad for it to return power?

  8. campyguy macrumors 68040

    Mar 21, 2014
    Portland / Seattle
    Start with this post:

    This web page includes a link to their Product Database.

    The VESA DisplayPort standard, Page 147 - quoted:
    3.2.2 DP_PWR Wire
    A standard DisplayPort cable must have no wire for the DP_PWR pin. Only captive cables supplied with cable powered Branch Devices or cables permanently attached to Sink Devices are permitted to have the wire for DP_PWR. These captive/attached cables must have a standard DisplayPort plug connector (as specified in Section 4.2.1) on one end only. The other end must either be permanently attached or have a custom connector.
    End quotation.

    Pin 20, "DP_PWR Power" should not be connected, it's a vestige connection that I haven't bothered researching. In the cables that I tested - those I called "junk" (I also tested some of the Monster Cable products some of my employees brought in on their own, and they's been binned and banned from my offices) the cables that I found to be returning power over Pin 20 are back-feeding 3.3v back into the video card (from the display), which can lead to sleep/wake/freeze issues. A lot of company are pushing out products that are not following the correct VESA DisplayPort Standards.

    Some companies, like Monoprice, do include a wire that connects Pin 20 on both ends, but they (Monoprice) has offered this "canned" quote to those who inquire:

    "In regards to pin 20, the short answer is that yes it is connected. The mini displayport side is a cable that connects to a PCB (printed circuit board) on the displayport side. The PCB is part of the connector on the displayport end, so technically none of the wires actually reach the displayport connector because they are wired directly into the PCB. In order for pin 20 to be active though, the device it is plugged into has to be designed to utilize the power from pin 20 and make that connection. If it is not designed for that, pin 20 would stay completely inert."

    That canned statement from Monoprice reads to me - this is me writing this bit, not them - is that they're producing a non-compliant/certified product and putting the proverbial turd in the display manufacturer's pocket to not provide power at Pin 20. Some of my Dell P2715Q displays did, the first version, and a certified cable addressed the sleep/freezing issues. For me, why spend 6 bucks on a cable from a company that doesn't supply a certified product and leaves it to the buyer to play roulette, when you can spend a few more bucks for a certified cable from a maker who works to protect its buyers. QED, for me - I'll stick with the Accell, Belkin, Eizo, and StarTech makers who work for me. FWIW, I write contracts and specifications for my engineering projects, it's a thing with me. Cheers!
  9. ugahairydawgs macrumors 68030


    Jun 10, 2010
  10. campyguy macrumors 68040

    Mar 21, 2014
    Portland / Seattle
    I read over that piece, they're batting .400 in that section...

    Hits: they linked to Accell and StarTech's products.
    Swings-and-misses: recommending Plugable's and CableMatter's product (all of which I've tested and had fail supplying power over Pin 20) and offering "which are all identical to one another but missing the aforementioned clip, work just as well if the Cable Matters cable is out of stock or more expensive" in that both Plugable and CableMatters have never made a compliant/certified DP product. FWIW, I did test the new USB-C cables for my two workstations (PCs) and both returned power over Pin 20, and then I returned them for a refund - my point here is that the products are not "identical", and both Plugable and CableMatters can't back up their claim as they're not on the DP Products Portal. I'd offer spending a few more dollars and buy from someone who takes the time to get it right. The Wirecutter doesn't get it right here either, and I've got a multi-tester that can back it up and a significant investment to protect with no affiliate links like The Wirecutter IMHO splays and splatters all over their pretty-much-sponsored posts...

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