U2720Q, MacBook Pro 2012 peripheral issues

Question

Hi, I have been using the Dell U2720Q monitor for 6 months and have a question. I have a Macbook Pro 2017 that I connect to the U2720Q using USB Type-C. It can charge and transfer audio video. I can also connect my peripherals connected to the U2720Q (mouse, keyboard). No problems here. I have an old MacBook Pro 2012 that I can connect to the U2720Q using the mDP to DP. I will need to use the charger for the laptop to allow it to display to the U2720Q. It can transfer the video and audio no problem. The issue is the peripherals that are connected to the U2720Q do not work with my old 2012 MacBook. My mouse and keyboard need to be connected to the MacBook instead of the U2720Q to work. I am not too sure if mDP to DP do not allow transfer of the peripheral information or something else. Anyone know the issue? Thanks!

XPS_Man · Accepted Answer

mDP to DP do not allow USB data transfer, only for video and audio.

I am quite surprised this 2012 MacBook doesn't have a USB Type-C port in it?

You can try a USB Type-C to USB-A cable. You may have one lying in your home, most cellphone comes with these now a days.

Page 27

jphughan · Answer

@RickDick Yes, DP to DP will have this issue because DP and Mini-DP are identical except for the physical shape of the connector and I believe a small difference in the amount of power they are required to provide (only enough to power active adapters, not much compared to USB at all). DisplayPort cables never supported carrying USB data. To do that, you need....a USB cable. The ability of a USB-C cable to carry power (in either direction) and USB data and video all over a single cable was an industry first. As for the C to A cable, if you care about USB 3.x speeds, make sure you get a cable specifically rated for USB 3.x. Some cables only have the pins and internal wiring to support USB 2.0 and power since they're meant to be used primarily for charging devices. Many of the C to A cables included with smartphones will be like that.

@XPS_Man USB-C didn't show up on laptops until 2015 or so. A 2012 laptop was way too early to have that.

RickDick · Answer

Thank You XPS_Man.   That is what I thought was the case as well. Does DP to DP have this issue? I will try the USB C to USB A cable.

RickyJohnson123 · Answer

Hi Jphughan,

I have the same monitor U2720Q and have a few questions.

1.If I build a gaming PC, do I just do DP to DP + USB-A to USB-C (the USB-C upstream for the monitor) in order to use peripherals?

2. Can I do DP -> DP but the head of the DP connects to USB-C converter and then plug into USB-C? (It says Alternate mode with DisplayPort 1.4) Does that mean I can transfer audio/video and use my peripherals at the same time? Or do I have to do 1. method?

Thanks!

jphughan · Answer

Option #1 will work.  Option #2 will not work because once again, a DisplayPort connector does not support carrying USB data.  So a USB-C to DisplayPort cable will only carry a video signal.  If you use that to connect a USB-C port on your system to a DisplayPort input on the display, then that will be just like using a DP to DP cable.  If you use it to connect the DP output on your system to the USB-C input on your display, it won't work at all because USB-C to DP cables don't work in that direction.  A regular DP output cannot feed a USB-C input.

RickyJohnson123 · Answer

Thank you very much for the reply

Monitors

Was this post helpful?