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undersmusic

macrumors newbie
Jan 9, 2020
3
1
So I got a replacement machine on Tuesday because of the coil whine issues I've been discussing in another thread, and after restoring my Time Machine backup, the display connected to the Pro Dock was set to 30Hz and couldn't be changed in System Preferences. I disconnected the machine from the dock and zapped the PRAM, which worked for me.

Since I don't know your exact setup, and if I was troubleshooting, I'd also try connecting the power adapter to the machine, as the dock cannot provide a full 96 watts of power the system's rated for. So it's possible the system's underpowered.


Have tried this
Don't blame the computer, it's the shoddy docks.

its not the dock because i've tried to connect both the original 96 watts power adapter and the external display connected directly through USB C - Displayport , same flickering problem remains.

Also have reset NVRAM + SMC before connecting external display, no luck.
 
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undersmusic

macrumors newbie
Jan 9, 2020
3
1
I solved my external display issue. while using the Caldigit Ts3 dock.

The refresh rate for my external display dissapeared when resolution was set to Default for Display.
When set to scaled the refresh rates dropdown appeared and was able to change to 60hz instead of 75hz.


Quite a noob solution and can't believe i didnt see this before. Hope this solves some of your display issues. If not, hope you have a nice day regardless.
 

ThunderSkunk

macrumors 68040
Dec 31, 2007
3,823
4,052
Milwaukee Area
Ok, I've got a couple old 30" ACD displays availble to try making work. Before I waste $100 on a pair of adapters to get them connected to the MBP16, I'm looking at the octopus of cables here and thinking, if you guys are having trouble with anything but a single direct line from the MBP to the display, the ACD's already got that line going from the display to DVI, through an adapter to MD, and I'll be stringing at least one more connection between it and the computer. As well, the built in hub requires the additional & separate USB2 line, which it sounds like shoulnd't be put inline with the display signal, so, there goes another couple ports... this is a lot of adapters plugged into adapters here. Maybe I just answered my own question & it's time to box the ACD's back up & move them out.

It'd be nice if someone like, I dunno, Apple maybe, also made a couple more USB-C cables since they've booted us all into the USB-C only era. Like a decent right-angle USB-C to Mini-B cable to get everyones accessories plugged in, or a USB-C cable for all the hundreds of thousands of ACD's out in the world. And who designed these adapters that place the brick 2" from your laptop instead of at the other end down the line. Like I want 3 of those ugly beasts cluttering up my workspace, as a constant reminder that I bought a computer that isn't compatible with anything else I own. Strangely, of all the cable mfg's in the world, options for every common connection I need my MBP to make are either completely missing or total junk.
 
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robvas

macrumors 68040
Mar 29, 2009
3,240
629
USA
Got rid of my 27" cinema displays when I bought my 2016...PITA to connect to USB-C, plus there are better monitors out nowadays
 

aeikenberry

macrumors newbie
Jan 13, 2020
18
21
Same Problem Here too Brother. Two Laptops returned

Did returning the laptops help? I'm having the same problem. Connecting 2 monitors works ok with the lid open, but when you close the lid, it crashes every time. I'm not sure if I should try to get a new laptop from Apple or see if it's resolved with software.
 

mightyjabba

macrumors 68000
Original poster
Sep 25, 2014
1,586
328
Tatooine
I am almost positive that returning computers doesn't help, if by "help" you mean that you will somehow get a replacement that works properly.
 
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MetroVoice

macrumors newbie
Jan 16, 2020
1
0
Just had another issue where waking my machine up caused all of the screens to start flashing on and off, and no amount of unplugging and replugging would fix it. I was able to unplug them all and get the internal display to work so that I could restart, but this is really not acceptable. Sure, waking from sleep seems to work most of the time, but even if it only has a problem once in every twenty times, it's hugely annoying and disruptive. I'm considering just not letting it sleep.
Same thing here, but noticed if the MBP is running on battery (power supply unplugged) my issue disappears, and the HDMI monitor works.
 

Bryce WBN

macrumors newbie
Dec 23, 2019
7
0
Antwerp, Ohio
10.15.3 beta 2 did not fix the problem. BTW there is a firmware update for the Caldigit Ts3+ that does fix a couple of the issues for some people.
 

Bryce WBN

macrumors newbie
Dec 23, 2019
7
0
Antwerp, Ohio
It looks like the official release of 10.15.3 may have fixed the problem. I plugged in this morning while the computer was still closed to test after I upgraded the other night and it's working!
 

sstenhjem

macrumors newbie
Feb 7, 2020
3
1
I just unboxed the 2019 MBP 16" yesterday got it all setup, took it to the office, unplugged the 2 monitors from 2016 MBP (that are working) and setup the new MBP, external monitors not even recognized by the MBP. Tried everything in this thread and others, called Apple support (no resolution), went through all tests with them, different USBC-HMDI cables, power adapters with HDMI-HDMI, tried other monitors, tried smart TV, Nothing is working, laptop closed or open, 1 monitor or 2 monitors. These ASUS Monitors are nothing special, ISP HD 1920x1080. I am wondering if all my cables are simple USBC and not Thunderbolt 3? Taking the MBP to Auth dealer to do some more testing.
 

sstenhjem

macrumors newbie
Feb 7, 2020
3
1
I just unboxed the 2019 MBP 16" yesterday got it all setup, took it to the office, unplugged the 2 monitors from 2016 MBP (that are working) and setup the new MBP, external monitors not even recognized by the MBP. Tried everything in this thread and others, called Apple support (no resolution), went through all tests with them, different USBC-HMDI cables, power adapters with HDMI-HDMI, tried other monitors, tried smart TV, Nothing is working, laptop closed or open, 1 monitor or 2 monitors. These ASUS Monitors are nothing special, ISP HD 1920x1080. I am wondering if all my cables are simple USBC and not Thunderbolt 3? Taking the MBP to Auth dealer to do some more testing.

Okay, did some more cable testing. Come to find out the other cables I was using or 30Hz and I found 1 that is 60hz and it works swimmingly!!! This might be the issue.
 

matram

macrumors 6502a
Sep 18, 2011
781
416
Sweden
I have had problems with a single monitor / beamer connected via HDMI to my 16”. It seems graphics switching is not working as it should. I end up with a flashing or black screen.

Catalina 10.15.3 improved things a lot.

It still seems the dGpu firmware still hangs and then the a reboot is needed to fix things.

I guess the AMD drivers need a lot more work.
 

Vishnu Kamath

macrumors newbie
Dec 30, 2019
8
1
So i got a 3rd Laptop, i think the problem is with the displayport configs on the dock. This time along with the laptop, i got a caldigit HDMI Dock. Now the laptop works fine but it feels kinda ****** that there is a bug in the display port outputs which causes these crashes.
 

sstenhjem

macrumors newbie
Feb 7, 2020
3
1
Okay, did some more cable testing. Come to find out the other cables I was using or 30Hz and I found 1 that is 60hz and it works swimmingly!!! This might be the issue.
Well the happiness was short lived. Monitors are working but now i am having the issue of the the MB tries to come out of sleep mode. Monitors just flicker and go black.
 
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martinblank

macrumors newbie
Feb 25, 2020
1
0
I'm not sure if this helps any but I was running into the flickering issue when I tried to plug 2 23" monitors into my mac. However, when the plugs were both plugged into the left side of the machine (Type-C) the dual monitors worked or if it was single monitor plugged into the left side. Any other variation did not work.
 

groove-agent

macrumors 68000
Jan 13, 2006
1,865
1,690
My 16" sh!ts the bed if I unplug the thunderbolt cable to my LG. It spontaneously crashes and reboots. Now I try to power off the MBP before connecting and disconnecting.
 

JR2W

macrumors newbie
Mar 5, 2020
2
0
I'm not sure if this helps any but I was running into the flickering issue when I tried to plug 2 23" monitors into my mac. However, when the plugs were both plugged into the left side of the machine (Type-C) the dual monitors worked or if it was single monitor plugged into the left side. Any other variation did not work.
This did help. Thx. Not all ports are created equal?
 

iMi

Suspended
Sep 13, 2014
1,624
3,200
I am having issues similar to the one described here, except I'm using one 27" UltraFine 5K monitor. It mostly works fine, but then from time to time it will not wake from sleep in clamshell mode. Unplugging the monitor and plugging it back in doesn't solve the issue. Opening the MBP16's screen while still being connected to the monitor does not resolve the issue. It just blinks on and off. Opening the computer screen AND disconnecting the monitor returns everything on the Mac to normal, but then reconnecting the monitor again causes blinking screens. I have to restart the computer for everything to return to normal.
 
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tom619

macrumors member
Oct 28, 2009
87
6
Seeing very similar issues when connecting to a Lenovo 4K monitor using the supplied usb-c cable. Any combination of turning the monitor off, plugging in my RJ45-USBc adapter, causes both displays to blink like hell before deciding to settle down, usually on the wrong resolution. Any help please?
 

JR2W

macrumors newbie
Mar 5, 2020
2
0
I poked around some more as the new issue I had after migrating to the left USB-C port caused 1 monitor to flicker/snow. The next best solution I found was to do an SMC reset. Still not a full fix, but at least it's not hourly/daily.
Traded altrnating blank monitors after sleep to flicker every other day.
 

Jocs7

macrumors newbie
Apr 25, 2020
2
0
I've tried two different thunderbolt docks with dual 1080p displays. The CalDigit Minidock HDMI version and a no name chinese dual hdml thunderbolt dock. Both of them work ok except they won't wake up from sleep. I was using it fine with my 2017 15 inch mbp on catalina, but after upgrading the the 16 inch it has the problem every time it wakes from sleep. Unplugging the dock and plugging it back has been working to wake up the displays.
I have this same issue with the 16” macbook pro and a Caldigit TS3+. Were you able to solve the problem? Or does anyone know how? Thanks!
 
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