Hello all,
I have two LG Ultrafine 27" displays and enjoy using them - 1) via USB-C/TB4 and 1) via HDMI. I want to connect both via USB-c to use the USB-A inputs on each display.
Question: Has anyone succeeded in connecting two (2) displays to an M1 Pro MacBook Pro? I do have a TB4 hub that I have tried with negative results. Am I missing something?
MacBook Pro Apple Silicon
Using the "shipped in the box" cables can be problematic. These are often "lowest bidder" cables and do not meet the TOP specs required for use on a Mac. Does that display work with your Thunderbolt cable?
what make&Model Dock, exactly?
The epilog - by unplugging/replugging the power connector to the back of each monitor, the USB-C cables worked! For some unknown reason, the monitors responded when the power was disconnected/reconnected - which may allow the Mac to query the devices (monitors).
The setup is TB4 cable from the clamshell 2022 M1 Pro MacBook Pro to the Alogic TB4 dock > 2 TB4 cables from the TB Dock to each monitor - success.
The glitch was the power connectors to the back of the monitors. This a friendly reminder to unplug/reattach the power plugs when trying to diagnose a problem.
I hope this helps someone.
Hello php4u,
This article explains more about connecting external monitors to your MacBook Pro: How many displays can be connected to MacBook Pro - Apple Support. If you are following the steps and guidance in this support article, please make sure that you are taking note of the appropriate connectors and test without additional hubs or adapters to make sure the cables are working correctly.
We hope this helps. Let us know if we can assist with anything else at all. Take care.
2nd Display Support: Dual/Mirroring*2nd Max. Resolution: 6016x3384 (6K) x2*
Details:* This model supports full native resolution on the interior display in addition to up to two external displays up to 6016x3384 (6K) at 60 Hz at over a billion colors.
Connect the second one with a short 40 G bits/sec rated USB-C cable or Thunderbolt-3 cable, and live happily ever after.
Your Dock should support up to two displays on one cable PROVIDED:
That cable is a genuine ThunderBolt cable and 0.8 meters long or shorter, AND
the first device (Display or Dock) is a genuine ThunderBolt device.
You may be having trouble getting two displays on one cable to work, because Mac display recognition is complicated..
The Mac uses a system that reminds me of “Plug and play” to determine what display is connected, and what its capabilities are.
To get a Mac display to become active, you need the Mac to query the display, and the display to answer with its name and capabilities. Otherwise, the display will not be shown as present, and no data will be sent to the display. "No signal detected" is generated by the DISPLAY, not by the Mac.
This query is only sent at certain times:
• at startup
• at wake from sleep — so momentarily sleeping and waking your Mac may work
• at insertion of the Mac-end of the display-cable, provided everything on that cable is ready-to-go
• hold the Option key while you click on the (Detect Display) button that will appear in Displays preferences (from another display)
so try doing some of those things and see if the display comes alive.
Thank you, Grant.
I will try your suggestions. I have a TB dock plugged into my M1 Pro MBP. I will try plugging each USB-C cable from each LG Ultrafine display into separate TB4 ports on the dock. I will also try two of the TB4 ports on the MBP.
I will report back on my results.
After some quick testing:
1) I tried a TB4 cable to monitor 1 and LG USB-C cable to monitor 2
2) I tried #1 using both the MBP and Dock ports
3) I rebooted the machine and tried "Detect Displays" to query the displays
I also tried a second 40GB USB-C aftermarket cable with the TB4 cable.
All with negative results.
ALogic TB4 dock
https://alogic.co/us/thunderbolt-4-blaze-docking-station.html
I can switch the TB cable to both monitors separately and each monitor works, the same is true with the LG USB-C cable and 40GB USB-C cable (all cables tested individually and work correctly).
That Dock should be able to support up to two displays on a MacBook Pro 14-in or 16-in or Mac Studio, provided it is connected with a genuine ThunderBolt cable shorter than 0.8 meters. the Mac cable may need to be plugged into the BACK port.
The 13-in Apple-Silicon MacBook Pro and Air only support one external display directly.
USB-C cables used for a display should have the SuperSpeed+ or SuperSpeed++ labels, and be under 1 meter in length.
which model-year MacBook Pro Apple-silicon and what screen size?
M1Pro MacBook Pro 14 inch.
So you cycled the power, by disconnecting the AC power cord to each display, and that cleared up the issues?
Let's hope this holds up for days on end.
Yes. So far, the testing is going well. Trying different apps and all seem to be working well. And, the USB ports on the back of each monitor work well too!
How to connect 2 monitors by USB-C to M1 Pro MacBook Pro
