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JonathanU

macrumors member
Original poster
Jun 3, 2008
34
0
London, UK
Hi,

I recently upgraded my 2013 MacBook Pro, which I used with two external Dell monitors (P2415Q). I managed to to connect them previously - one to the old Mini Display Port and one to the HDMI port. It was a bit slow at startup but it worked.

I've now upgraded to a 2020 MacBook Pro, and I assumed that I would buy two USB C to Mini display port adapters, and just plug them in and it would work. One of of the monitors comes on ok, but but the other one doesn't. I've used the Displayport out adapter on one of the Dells to try to connect to the Mini DisplayPort on the other to daisy chain, but no luck there either. Am I bumping up against a driver issue or something, or just missing something obvious?

Thanks in advance

Jon.
 

Stephen.R

Suspended
Nov 2, 2018
4,356
4,746
Thailand
As you have two adapters already, you have checked that the one that doesn't work is on the correct input source (i.e. it's not waiting for a HDMI signal), right?

If you plug them in individually do they both work or does only one specific display work? If only one, have you tried swapping the adapters/ports.


After all that, if you want to free up a TB3/USB-C port, I can highly recommend the TB3 > Dual DP adapters (e.g. I have this one from OWC: https://eshop.macsales.com/item/OWC/TB3ADP2DP/). I use mine with two displays the same as yours from a Mac mini. Works fantastically, and would be a bigger bonus with a portable like that I imagine.
 

JonathanU

macrumors member
Original poster
Jun 3, 2008
34
0
London, UK
I have played around with it, and it turns out that the monitors work fine in the rear two USB-C ports of the MacBook Pro, but not the front two, as you're looking at the computer. I guess they're subtly different somehow?
 

Stephen.R

Suspended
Nov 2, 2018
4,356
4,746
Thailand
... that's quite unexpected, I would try contacting Apple support and check if that's expected behaviour? Might be a fault.
 

mfram

Contributor
Jan 23, 2010
1,322
362
San Diego, CA USA
I have the same display adapter as Stephen.R running on a 2020 13" MBP. I am able to run an LG and Dell monitor both @ 4K/60Hz with that adapter. It works great on my MBP.
 
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