You can make a difference in the Apple Support Community!

When you sign up with your Apple Account, you can provide valuable feedback to other community members by upvoting helpful replies and User Tips.

Looks like no one’s replied in a while. To start the conversation again, simply ask a new question.

Intermittent black-outs when using USB-C ports on a 4k 10 bit display (Benq SW271) with 2018 Mac Mini

Hello,

I have seen many posts and read many articles online addressing the strange situation of "intermittent black-outs" that may be a result of a whole host of reasons. I have been through hours of tech support with Apple as well as with Benq an of course, no one is seeing any reasons to this madness.


In short, I have a 2018 i7 Mac Mini with the Intel UHD 630 GPU.


  • PROCESSOR065-C70X3.2GHz 6-core Core i7
  • MEMORY065-C75H8GB 2666MHz DDR4
  • STORAGE065-C714512GB SSD
  • GRAPHICS065-C717Intel UHD Graphics 630
  • ETHERNET ADAPTER065-C7491GB Ethernet Port
  • COUNTRY KIT065-C72VCOUNTRY KIT


When I am connected to my Benq SW271 via USB-C to USB-C or from USB-C to DP I experience random and intermittent moments where my screen will go black for 1-3 seconds, then come right back on. I am not losing power and the machine is not going to sleep.


When I use HDMI to HDMI i do not have this issue, the machine and display perform as one would expect. I would prefer to use the USB-C ports on the mini for the display so that I can take advantage of the 10 bit color depth that the Benq SW271 offers. When using HDMI you color depth will be "limited" to 8 bit.


I understand that most applications currently do not support 10 bit color, but photoshop does and I am in the photographic field. I have enabled "30 bit color depth" in photoshop and in a subtle way you can tell a difference from 10 bit to 8 bit as gradations are very smooth. But, with the display going black at random times and with no particular reason, this set-up has proven to be one that I can not use.


Albeit HDMI is not "BAD", in-fact it looks great, but it is not as good as what you are able to see when you are able to take full advantage of the 10 bit color depth.


Any advise? I know that technically this graphics card should be able to support 4k at 10 bit, but it seems that it chokes. I have tried multiple power sources and outlets (APC/non APC) and have switched out cables and brands several times. I have even moved my set-up to another location in my home as it was pointed out the RF or some other frequency could be causing the issue, but this did not resolve the issue.


I have connected a Mac Book Pro via TB to USB-C to this display and have not had any issues. The particular video card in this mac does not support 10 bit as it is in Intel Iris Pro, but it does not seem to be a port issue on the display.


Thanks in advance

Posted on Aug 4, 2020 9:14 AM

Reply
Question marked as Top-ranking reply

Posted on Aug 5, 2020 2:07 AM

YMMV but I had random short blackouts on my Mac mini 2018 & Thunderbolt LG 4K display when I used old Firewire external disks via adapters. I then got a new USB3 OWC dual dock and no more blackouts after that.

Similar questions

7 replies

Aug 4, 2020 12:12 PM in response to Todd Schweikert

I don’t think that will help because of

and


Based on the documentation, it appears BenQ does not have what it takes to support 10 bits x 4K x 60 Hz on its USB-C. In fact, doubtful they support 4K 60 10 bits on any of their ports. If you do a search for “10 bit” on the user manual, you’ll come up empty. Their 10 bit claim is probably limited to the panel glass (and possibly Win 10 over DP 1.4).


That said, resolution exaggeration/hype is an industry-side disease 😂. Figure out what works best for you and move on. Not worth a call to any Tech Support. Good luck!


Aug 4, 2020 11:26 AM in response to Todd Schweikert

USB-C on this BenQ monitor isn’t a great way to push it to the max because it reserves bandwidth for USB 3/USB 2 at the cost of resolution/frequency/bits over which you have no control. Which is why your HDMI is working perfectly and your USB-C isn’t.


The BenQ-touted 10 bit support is a better bet on Win10 using DP 1.4 (Mac stops at DP 1.2).


Short summary: there’s no fix. I would stick to HDMI.

Aug 4, 2020 12:53 PM in response to hcsitas

Much appreciated (although not the news I would want). I have been on with apple tech support for hours over the past 3 months, as well as sending log file after log file for their engineers while my screen "blinks" at me several times per hour. This straightforward and simple answer is the only thing I have seen that makes any sense.


Thank you for your replies.

Intermittent black-outs when using USB-C ports on a 4k 10 bit display (Benq SW271) with 2018 Mac Mini

Welcome to Apple Support Community
A forum where Apple customers help each other with their products. Get started with your Apple Account.