Displayport cables must not use pin 20 (warning)

Discussion in 'Displays' started by evilsofa, Jan 27, 2014.

  1. evilsofa

    evilsofa [H]ardForum Junkie

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    I post this because a lot of users here are now using DP for the first time with 4K displays.

    I have recently bought two Benq BL2411PT, and I started looking for Displayport to Mini Displayport cables to connect them to a pair of Mac Minis (which have Thunderbolt ports that accept Mini Displayport). I went to Monoprice and noticed customer complaints about their Displayport cables being non-compliant.

    There are apparently a lot of Displayport cables that connect pin 20, which is not supposed to be done. Connecting pin 20 feeds 3.3v back into your video card, which causes issues, and may even damage the video card so that it may affect whatever else you plug into it later. Belkin and Startech cables are noted to be non-compliant, and in this thread Monoprice is also noted to be non-compliant.

    Here's VESA's official comments on the issue, and if you go to their certified product database, you can search for Cables and see their very short list of cables that are known to be compliant and not connect pin 20.

    The only DP to mini-DP cables listed as compliant are made by Accell. $12 for the 1 meter and $20 for the 2 meter, quite a bit more than Monoprice's $5 cables. I don't see any evidence that Monoprice has noticed its customers' complaints, which surprises me.

    Edit: In a post later in this thread, I describe how Monoprice got back to me and explained that this is not an issue on their Displayport cables:

    "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."

    I am now using a Monoprice Displayport cable between my Mac Mini and my Benq monitor without any problems.
     
    Last edited: Aug 10, 2014
  2. Venomous

    Venomous Gawd

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    Well I've been using DP ever since eyefinity debuted with an eyefinity6 card. I've used the monoprice cables without issues and continue to do so with my dual 280s. These are standard DP on one end and mini DP on the other. I'm not having or noticing any issues using their cables.
     
  3. Bluesun311

    Bluesun311 2[H]4U

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  4. Webhead

    Webhead Gawd

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    That post from Anandtech is 2 years old. I'd hope that if Monoprice had an issue such as this with pin 20 that it would have been resolved a long time ago. Over the weekend, I just ordered p/n 8119 (Mini DisplayPort to HDMI®, DVI & DisplayPort Adapter) to use with my Surface Pro 2. Will have to test when I receive it to make sure things work.

    I'm pretty sure the cables I use for my crApple Cinema Display with my PC were ordered from Monoprice. No problems at all for a couple years now.
     
  5. phillyboy

    phillyboy [H]ard|Gawd

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    Aten brought up the issue to me before when I had a mini-displayport KVM that would not keep its display data saved. They had issues in the past with non-VESA cables causing issues with their displayport KVMs.
     
  6. evilsofa

    evilsofa [H]ardForum Junkie

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    I had an interesting chat with Monoprice today, when it occurred to me that I should just ask them directly. At the beginning of the chat, the tech went to check the info on their Displayport cables and came back with:

    "unfortunately pin 20 is not connected on our Displayport cable"

    I went on to explain that this was a good thing and why. I think we might see the product descriptions change on Monoprice's Displayport cables soon.
     
  7. jmilcher

    jmilcher [H]ardness Supreme

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    It's been corrected. This is no longer an issue.
     
  8. crawfish

    crawfish n00b

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  9. evilsofa

    evilsofa [H]ardForum Junkie

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    Their lead tech got back to me by email. I was asking them specifically about PID 6006 and 6007, mini-Displayport to Displayport cables. This is what he said:

    "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."

    So I shall go ahead and buy Monoprice cables then!
     
  10. ST Nathan

    ST Nathan n00b

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    Just a note for anyone having problems with non-compliant (pin 20 connected) DP cables. A quick and easy fix is to take a very thin (about 1/16") strip of electrical tape, and wrap it around pin 20 on one of the connectors. Pin 20 is the one closest to the angled notch in the connector. As long as you're careful to completely cover pin 20, and not the adjacent pin 18, that will cause the cable to act as if that wire wasn't connected, which is how it's supposed to be.

    This is a lot easier than trying to pull the pin out, and it's a lot harder (like, impossible) to break your cable doing it. Took me about 45 seconds per cable, and now everything works!
     
  11. Gronnie

    Gronnie [H]Lite

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    So does anyone know if the Monoprice ones are ok to buy or not? I need to buy a new Mini DP to DP cable as the one I am using with my Dell U3011 is definitely not compatible and I am having sleep problems.

    This is the one I currently use: http://www.amazon.com/Cable-Matters...p/B004CAGDUA/ref=cm_cr_pr_product_top?ie=UTF8

    I know for sure this one from Accell is compliant but I would rather not spend $20 if I can spend <$5 for the same thing: http://www.amazon.com/gp/product/B00A7R9I22/ref=ox_sc_act_title_1?ie=UTF8&psc=1&smid=ATVPDKIKX0DER

    This is the Monprice one I am looking at: https://www.monoprice.com/Product?c_id=102&cp_id=10246&cs_id=1024606&p_id=6007&seq=1&format=2
     
    Last edited: Aug 9, 2014
  12. evilsofa

    evilsofa [H]ardForum Junkie

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    Monoprice Displayports are compliant. See my previous post.
     
  13. Gronnie

    Gronnie [H]Lite

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    I didn't quite understand your post.
     
  14. Kwisatz Haderach

    Kwisatz Haderach Gawd

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    I have that Accell cable on my u3011. It won't make any difference with your sleep problem. I have them too. I bought a monoprice mini dp to dvi cable, and the u2007 goes to sleep flawlessly every time. It's the u3011 that's flawed. I can say you can definitely feel a difference in build quality of the cables between Accell and Monoprice. They weight less and are way more pliable.
     
  15. Nenu

    Nenu [H]ardened

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    He is saying that pin 20 from the device (monitor on normal display port) isnt connected directly to the gfx card (mini display port end), it is connected to the adapters PCB only.
    The PCB doesnt make a connection of pin 20 to the mini display port side.

    He also makes the point that the display will need to make use of pin 20 in order for it to even be connected to the PCB.
    Implying it isnt a likely event.
    Not that it matters if it isnt used for anything by the adapter.
     
  16. Gronnie

    Gronnie [H]Lite

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    Well that's a bummer.

    I had read a lot and it seemed like others were having problems with U3011 waking from sleep. Mine won't even go to sleep usually, even when I shut down the computer. I also have a problem of when I shut down my computer, the "Windows is shutting down" image stays on the monitor even long after the computer is completely off.

    Are you saying at the end that the Accell cable is much better build quality? Do you think it is worth the price difference? The relative price difference is 300%, which is quite large. However, in absolute terms, $15 won't exactly break the bank.
     
    Last edited: Aug 10, 2014
  17. Gronnie

    Gronnie [H]Lite

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    Thanks for clarifying. I thought it was something like that, but wasn't sure.
     
  18. Kwisatz Haderach

    Kwisatz Haderach Gawd

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    Mine does the stuck screen at shutdown too. For the price, and what I know, I think the Monoprice cable will be fine. But as a disclaimer, I have only had their cable a few days. I can't judge long term yet.
     
  19. Gronnie

    Gronnie [H]Lite

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    Great. That will be perfect then. I was planning on making a Monoprice order already. Since I already will have to pay shipping anyways, might as well pick one up.
     
  20. Gronnie

    Gronnie [H]Lite

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    If anyone is interested the Accell VESA certified cable has dropped to $13.62 on Amazon.
     
  21. VulcaN

    VulcaN [H]ard|Gawd

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  22. Bill_F

    Bill_F n00b

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    I disassembled a mono-price cable back in 2012 and pin 20 was not connected on both ends. Their cables are perfectly safe to use and I have tested many different ones they make and they all worked.
     
  23. sblantipodi

    sblantipodi 2[H]4U

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    I'm having problem with my display port
    http://hardforum.com/showthread.php?p=1041188717

    I don't know if this could depend on the cable.
    How can I check if my cable is connecting the 20 pin ? Is there a way to check this?

    Can you suggest a good cable that doesn't connect the 20 pin?
    Thanks.
     
  24. Bladestorm

    Bladestorm [H]ard|Gawd

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    Could this be why I was having random video signal loss and black screens on my new 4K monitor? I was initially using the same DP cable from my old 1440p monitor, and when I switched to the cable that came with the new monitor the problem went away.
     
  25. gan7114

    gan7114 Limp Gawd

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    The thing with DP is that it is amazing when it does work, and headache inducing when it doesn't. I recently encountered intermittent issues with DP when running my Dell U2713H. I finally just went with it, trusted VESA's certified vendor list, and ordered the 6ft Accell mDP-to-mDP cable for $20. The cable has worked flawlessly since the first connection.

    My first rule of thumb when connecting a monitor to a VGA card via DP is use a cable with twin ends. Meaning, either a full DP/full DP, or mDP/mDP cable. I'm just not a fan of mixed ends. Most new monitors today come with at least a full DP port, some come with both a full and a mini. I really wish AMD and NVIDIA would press their vendors to choose either/or for consistency, or even provide both and throw out DVI.
     
    Last edited: Oct 27, 2014
  26. sblantipodi

    sblantipodi 2[H]4U

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    is there a way to pull off the 20 pin on my cable, I would like to see if this is the problem before ordering a new cable.
     
  27. gan7114

    gan7114 Limp Gawd

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    I would not recommend that. You risk damaging your system. Better to just order the cable you need from a certified vendor at this point.
     
  28. Paragon54

    Paragon54 Limp Gawd

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    I don't know if this works or not because I haven't tried it yet, but read this post by Serko70 on the GeForce Forums:

    I have the same problem. It's not the port or cable as it works during boot. It is Windows drivers not properly recognizing displayports!. I found this solution elsewhere. Give it a try:

    Description of Solution: It is honestly as if the driver install the first time happens incorrectly and then it doesn't do plug n play correctly thereafter. So I tell device manager to show me nonpresent devices and then i uninstall them. The next time it connects it will redo the plug and play.
    Solution that worked for me:

    1. Click Start > Run.
    2. Type cmd and press Enter.
    3. At the command prompt, run this command: Note: In Windows 2008 and Windows 7, open the command prompt using the Run as Administrator option.
      set devmgr_show_nonpresent_devices=1 Note: If this command does not work (a possibility in Windows Server 2000 and 2003), you may need to add the parameter to Windows and set its value:
      1. Right-click the My Computer desktop icon and choose Properties.
      2. Click the Advanced tab and select Environment Variables.
      3. In the System variables section, click New.
      4. Set the Variable name to devmgr_show_nonpresent_devices and set the Variable value to 1 to enable the parameter.
      5. Click OK to add the variable to Windows.
    4. Start the Device Manager by running this command from the same command prompt:
      start devmgmt.msc
    5. Click View > Show Hidden Devices.
    6. Expand the Monitors tree (click the plus sign next to the Monitors entry).
    7. Right-click the dimmed Monitors, then click Uninstall.
    8. Once all of the grayed out Monitors are uninstalled, reconnect your monitor
     
  29. sblantipodi

    sblantipodi 2[H]4U

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    I have tried pulling the pin and I damaged the cable.
    That cheap cable is surely connecting the 20 pin so I put it in the junk.

    Is there a 100% 19pin cable on amazon.co.uk?
     
  30. Paragon54

    Paragon54 Limp Gawd

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    I'm not sure this is always a cable issue...There are a number of people having the same issue with the GTX 970 and 980. I've read lots of threads and it doesn't seem to be isolated to one manufacturer. I have a new ASUS Strix 970 and I've tried several cables and all outputs work fine except for the display port. The display port is recognized when the computer boots and then it loses signal and the monitor goes to sleep.

    I've tried two monitors as well. I posted one solution a couple of posts back that a member on the EVGA forum came up with, but I've been a little dubious to try it. The GPU works well with a DVI cable and my monitor does not require display port. I would have RMA'ed the card but I've read of several people that did just that only to have the same issue with the replacement they received.
     
  31. gan7114

    gan7114 Limp Gawd

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    All DP cables have 20 pins, even mDP. I think you're proceeding down the wrong path here. Start by getting a cable you know will work- a certified one- and from there, you can narrow down the list of suspects. It could be driver related, either with your VGA card or Windows (or both, and I'm not sure which you use). I doubt it is your monitor.

    I'm using Win7, a PNY branded 970 (reference), and I'm connected to my Dell U2713H with a mDP/mDP cable. No issues at all.
     
  32. Paragon54

    Paragon54 Limp Gawd

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    I just downloaded the newest drivers which are about three days old. I removed the old drivers with REVO and performed a clean installation except for the two 3D drivers which I don't use. The GPU is now working as it should with displayport.
     
  33. evilsofa

    evilsofa [H]ardForum Junkie

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    Just a reminder that the 20th pin is not a problem with Monoprice DP cables, and shouldn't be in other properly assembled DP cables. Please have the patience to read past the first sentence.

    "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."
     
  34. sblantipodi

    sblantipodi 2[H]4U

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    EIZO PP200-BK cable is on my desk, I hope that this will solve my problem.
    At least, this is a certified quality cable. This evening I will try it as soon as I return home
     
  35. jojo69

    jojo69 [H]ardForum Junkie

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    yeah, I have read that 4 times now and it makes no more sense than the first time

    that description is incomplete at best
     
  36. evilsofa

    evilsofa [H]ardForum Junkie

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    The PCB is like a tiny little computer that detects if the device is designed to pull power from pin 20. If the device isn't asking for power from pin 20, pin 20 not turned on and the problem described in my OP cannot happen.
     
  37. Lady Fitzgerald

    Lady Fitzgerald n00b

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    PCB = Printed Circuit Board
     
  38. TESLA

    TESLA Gawd

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    It sounds like at lest some manufacturers are correcting this issue, which is good to see.

    When I first purchased my current work/side project laptop, the best connection available to me was Mini DisplayPort, and I soon learned that the Mini DisplayPort cable market was a minefield of non-compliance (which would cause dropouts, undesired resolution(s), and sleep issues in my particular laptop model). But this was several years ago.

    For reference, I too used an Accell cable with no issues:
    http://smile.amazon.com/gp/product/B004065DAC/

    Anyway, it is pretty disheartening that so many manufacturers skimped on their compliance.
     
  39. sblantipodi

    sblantipodi 2[H]4U

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    spent 30€ for a cable and I solved nothing.
     
  40. dragonageinquisition

    dragonageinquisition Gawd

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    The stardock (sp?) 26 awg cables on Amazon seem to have live 20 pins still.