2015 13" rMBP completely freezing when resuming from sleep if I'm connected to external display

Discussion in 'macOS Sierra (10.12)' started by matt2053, Dec 19, 2016.

  1. matt2053 macrumors 6502a

    Joined:
    Jul 8, 2012
    #1
    I frequently am having complete system freezes when I resume from sleep.

    It seems to only happen if I am connected to my external display (Dell P2715Q).

    The symptom is that the screen is complete frozen on my MacBook Pro, no signal goes to the external display, and the system is completely locked up to where I cannot even press the trackpad.

    To recover I have to power off completely and then I get the "your computer restarted due to a problem" message.

    Anyone else facing this issue?
     
  2. campyguy macrumors 68040

    Joined:
    Mar 21, 2014
    Location:
    Portland / Seattle
    #2
    Two bits of advice, from a P2715Q owner. First, with about 20 of these in both my home and two of my offices we had plenty of issues with waking from sleep and freezing - on Macs (including my late 2013 rMBP) and Win 7 Pro/Win 8.1 Pro (Win 10 Pro came out after I made some hardware changes). The fix was to ditch the stock COXOC cables and switch to a cable listed on the DP.org Products Portal - seriously, the sleep and freezing issues completely disappeared.

    Second bit, I suggest both resetting your display using the OSM "Factory Reset" option (under "Others") and removing the DisplayVendorID-10ac folder in the Overrides folder (/System/Library/Displays/Contents/Resources/Overrides) then rebooting; that folder contains the relevant information that tells your Mac what the attached display is capable of - that file may be corrupted; the 10ac folder will be reconstructed after the reboot. The non-certified COXOC cable doesn't fully convey EDID data between your Mac and the display, and returns power from the display over Pin 20 to your Mac's graphics card - which can lead to that freezing issue I used to experience and is likely the cause of your issues. You should also consider unplugging your P2715Q next time this happens - it'll help reset the connection between your display and your Mac, but it won't fix the underlying issue at hand that a proper cable will fix. And, I do know that the stock cable has the "DP" certification symbol on it, but my multimeter showed me that that's a false claim borne out more than 5 years ago. Cheers!
     
  3. matt2053 thread starter macrumors 6502a

    Joined:
    Jul 8, 2012
    #3
    Hi! Thanks for the advice. Two things.

    What about an Apple Thunderbolt Cable-- will this work? http://www.apple.com/shop/product/MD861LL/A/apple-thunderbolt-cable-20-m

    Yeah, I've noticed that. That's one reason why I was starting to suspect the cable (which you confirmed is likely the issue). When I resume from sleep, sometimes everything is normal. But other times, I'll notice some graphical flickering on the 2nd display. When this happens, I've learned that I can un-plug and re-plug the external display and it seems to solve it. But if I don't catch it in time, or if I don't notice the flickering at all, the entire system freezes.

    Anyway, thanks so much for sharing your knowledge.
     
  4. campyguy macrumors 68040

    Joined:
    Mar 21, 2014
    Location:
    Portland / Seattle
    #4
    The TB cable absolutely will not work - I help a few other MR posters through this not too long ago. The TB cable is DP 1.1a compliant and the P2715Q requires DP 1.2 - and IMHO Apple started cracking down on specs with Sierra. The COXOC cable will carry DP 1.2 but the ones I've tested carry power over Pin 20 - which shouldn't happen (I read plenty about this on [H]ard|Forum - so props to them; I linked to the thread that got me going on this several months ago - if you use a web search for "displayport power over Pin 20" you'll likely find it in short order...).

    The secondary issue, for me, is throughput. I bought a few cables from several brands, including StarTech and CableMatters, before knowing more about this niche industry. What I had going for me was a few workstations in my company with Eizo displays connected that NEVER caused me problems. Eizo's cables that shipped with the displays are in the certified products portal. Over time, I read that marketing crap for the cables on Amazon/Newegg and started paying attention - seeing DisplayPort 1.2 "compatible" and other specs that now make sense to me. The cables I'm using are these:
    http://www.accellcables.com/collect...aav-mini-displayport-to-displayport-1-2-cable

    For the Accell DP 1.2 cables (linked above), the product info tells me that they're 2160p (UHD) capable with 5.4 Gbps per lane throughput - the biggest pipes I can find in a mDP>DP cable, and they're in the DP products portal. StarTech's cables were 1600p when I bought them, and they're also DP certified - telling me on their site that their cables use 19 conductors (with the 20th - Pin 20) disabled or blocked in hardware - but they don't tell me their throughput; I've found them to be updated to 2160p (https://www.startech.com/Cables/Aud...r-Cable-Male-to-Male-Mini-DP-to-DP~MDP2DPMM10), so there's two nice options for you and I'll consider them again when I need additional cables. Look for HBR2 to offer that they're capable of 2160p.

    And, those cables are way cheaper than a new TB cable...

    About the flickering issue, there's one additional bit that could be at issue - some of the P2715Q displays had issues with sleep and freezing, and Dell is on the 3rd hardware revision. I have some initial builds that froze, and some 3rd revision builds that froze - all were solved with a certified cable. What gets me is Dell sells us these $500-$600 displays and gimps them with a 2 dollar cable that doesn't meet the specs that their displays are built to. I'm confusedededed about this business decision. Cheers!
     
  5. matt2053 thread starter macrumors 6502a

    Joined:
    Jul 8, 2012
    #5
    Thanks again for the help.

    I'm ordering the ones from StarTech and I will let you know how they work out.
     

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