Trouble connecting 27" LED Cinema Display to Mac Mini M4

As I read the tech specs for the Mac mini M4, it seems that the rear Thunderbolt/USB ports are the preferred ports for DisplayPort video output.

Mac mini - Technical Specifications - Apple

❝ M4

Simultaneously supports up to three displays:

• Up to three displays: Two displays with up to 6K resolution at 60Hz over Thunderbolt and one display with up to 5K resolution at 60Hz over Thunderbolt or 4K resolution at 60Hz over HDMI
• Up to two displays: One display with up to 5K resolution at 60Hz over Thunderbolt and one display with up to 8K resolution at 60Hz or 4K resolution at 240Hz over Thunderbolt or HDMI

Thunderbolt 4 digital video output

• Support for native DisplayPort 1.4 output over USB-C ❞

❝ On back (M4):

• Gigabit Ethernet port (configurable to 10Gb Ethernet)
• HDMI port

Three Thunderbolt 4 (USB-C) ports with support for:

• Thunderbolt 4 (up to 40Gb/s)
• USB 4 (up to 40Gb/s)
• DisplayPort ❞

It may be that the DP adapters you bought do not meet spec. Apple's devices can be very finicky where adapters and peripheral accessories are concerned. You might give the folks at OWC/macsales a call and see what they offer and/or recommend for cabling.

Yes, although after multiple tries. The solution that worked used https://www.amazon.com/dp/B07V828R4Q?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 for one monitor through one of the Thunderbolt 5 rear ports, and https://www.amazon.com/dp/B099Z3P12J?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 through the HDMI port. Both displays work great.

I don't know how to decode the model number "MC007LL/A", but my question would be whether these ARE 27" LED Cinema Displays. Apple made TWO similar 27" displays.

• The 27" LED Cinema Display has a hydra cable with THREE heads: Mini DisplayPort, USB, MagSafe. It requires DisplayPort input. Use a third-party USB-C (male) to Mini DisplayPort (female) adapter. There are lots of those to be found (Web/mail-order).
• The 27" Apple Thunderbolt Display has a hydra cable with TWO heads: Thunderbolt (mDP-type connector) and MagSafe. It requires Thunderbolt input. Use an Apple Thunderbolt 3-to-2 adapter.

If you use the wrong type of adapter for the display, the plugs will physically fit, but the signal format will be wrong (e.g., feeding a DisplayPort signal to a Thunderbolt Display),and you won't get signal.

With old Macs that had Thunderbolt 1 & 2 ports, those ports carried BOTH Thunderbolt and DIsplayPort signals, so you could have plugged the hydra cable from EITHER of the above displays into the old Mac and it would have just worked.

The first picture shown the two different Answin adapters that I used, one into the Thunderbolt 5 port, one into the HDMI port. The specific products that I purchased from Amazon are (1) https://www.amazon.com/dp/B07V828R4Q?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 and (2) https://www.amazon.com/dp/B099Z3P12J?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 The last pic is of the two Apple LED Cinema Displays (Part Number MC007/LL/A)that I use. The Mac Mini M4 Pro is a 14 Core CPU/20-Core GPU, 64GB, 4TB) Hope this helps.

The Answin Thunderbolt to Mini DisplayPort Adapter would only work for one monitor. After that, I tried the Elecbee HDMI to Mini DisplayPort Adapter. While the screen came on, it was very yellowed, The Answin adapter solved this.

Dean Heistad wrote:

I've tried on both monitors, with both front USB-C ports on the Mac Mini.

That won't work. Those ports carry USB only. They do not support DisplayPort Alt Mode and cannot provide the signal that a display adapter needs to function.

I've also tried initially in one of the rear Thunderbolt 4 ports before I learned enough to know that wouldn't work.

The Thunderbolt ports and the HDMI port on the back of the Mac mini are the only ones that carry video signals. The Thunderbolt ports are where you should plug in any USB-C to Mini DisplayPort adapter you are trying to use. These are the ports that also carry DisplayPort Alt Mode signals.

Do you know the steps you took and which of the several adapters mentioned? I have both 2-plug and 3-plug versions of Cinema Display and can’t get either to work…But I haven’t tried going through an OWC TB hub either. That I could do.

Re: “I have both 2-plug and 3-plug versions of Cinema Display and can’t get either to work…”

Apple made two similar 27” displays. The one with a two-headed hydra cable is NOT a Cinema Display. It is a Thunderbolt Display (model A1407) that requires Thunderbolt input. The correct adapter for it is the Apple Thunderbolt 3-to-2 adapter. A USB-C (male) to Mini DisplayPort )female) adapter will have connectors that physically fit, but will provide the wrong kind of signal.

That Apple Thunderbolt 3 to 2 adapter is NOT the one you want for a Mini DisplayPort display like the 27” LED Cinema Display (model A1316, with a three-headed hydra cable). It does not know how to pretend to be a mDP on the TB2 side. There you would want a USB-C (male) to Mini DisplayPort (female) adapter.

This is my setup.

Mac Mini M4 Pro (14-core CPU, 20 Core GPU, 64GB, 4TB)

Two 27” Apple LED Cinema Displays (one cable with three connectors: Mini DisplayPort with audio support, universal MagSafe (up to 85W), USB 2.0)

One Answin HDMI to Mini DisplayPort Adapter https://www.amazon.com/dp/B099Z3P12J?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1 to connect one Apple LED Cinema Display thru the HDMI port.

One Answin USB-C to Mini Displayport Adapter https://www.amazon.com/gp/product/B07V828R4Q/ref=ppx_yo_dt_b_search_asin_title?ie=UTF8&th=1 to connect one Apple LED Cinema Display thru the middle Thunderbolt port on the back of the Mac Mini.

Two https://www.amazon.com/dp/B08HZ6PS61?ref=ppx_yo2ov_dt_b_fed_asin_title (this is a 2-pack) to connect the USB 2.0 connections from each Apple LED Cinema Display Apple to the left and right Thunderbolt ports on the back of the Mac Mini. (Needed for brightness control and iSight camera on the displays).

This setup provides full functionality for both Apple LED Cinema Displays.