Mac Studio – Dell HDMI-connected monitor will not wake up

that Dell UP3214Qt appears to feature 4K resolution at up to 10 bits/color, but

only 60 Hz refresh (none higher AND none lower)

Interfaces include

HDMI 1.4

DisplayPort 1.2 and Mini DisplayPort

HDMI 1.4 can only run 4K at up to 30 Hz and ONLY when set to 8 bits/color. otherwise, resolution must be set lower to get a picture over HDMI.

NB >> 8 bits/color HDMI is all your older 2010-2013 and "trash can" era Macs produced.

But since your display does not go as low as 30 Hz, you likely still can't get a picture.

HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"PREMIUM High Speed HDMI cable" or that + "with Ethernet" (up to 4K at 30Hz) --OR--

“ULTRA High Speed HDMI cable" or that + "48G" (supports higher resolutions and backward-compatible)

Cables with No Certification tags are good for your standard 720p TV set, and not much more.

Cables 'shipped in the box' with many displays can be "lowest bidder" cables that are not up to high-end display use. Cables with no markings 'found' behind your TV set are unlikely to be good enough.

HDMI was invented for HD TV sets. it works great at its original resolution of 720i or 720p. At higher resolutions, it quickly develops issues that are complex to solve, and the cables and adapters required to solve are NOT intuitive.

<< is it worth getting a USB-C to DisplayPort adapter so I can connect to my Mac Studio via the monitor’s DisplayPort instead of HDMI? >>

Absolutely, YES!

Be certain the cables involved are each no longer than ONE meter maximum.

longest would be

USB-C up to one meter -- adapter -- Display Port up to one meter

^-- but the sexes of the most commonly available adapters and cables do not support that directly

more typically:

adapter/cable USB-C to DisplayPort, one meter maximum.

DisplayPort 1.2 supports 4K at 10 bits/color up to 60 Hz directly, and higher with Display Stream compression.

<< I’m using a 2m “High Speed HDMI cable with Ethernet”. >>

NOT good enough. You need at least PREMIUM cable, and

ULTRA is better and backward compatible.

The Apple standard for its built-in hardware-accelerated displays, makes them suitable for full-motion video for production/display of cinema-quality video. Folks really are producing commercial feature films on Apple equipment, so It MUST meet the highest standards. That can not tolerate any dropped frames, and NO dropouts or partial-blank scan lines due to memory under-runs or Transmit errors due to low-spec or overly long cables. 

These acceptable settings are obtained by a query to the display itself. In most recent versions of MacOS, no transmit errors are tolerated, or the display will drop out. 

Under Windows, you manually choose the settings you prefer, or download a popular "Driver" (which is actually a package of resolutions and setting thought to be good ones).  Whatever happens is your problem.

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HDMI cables you want for HDMI-only Displays (higher resolutions than 720p TV sets) are marked as Certified with an anti-counterfeiting tag and are labeled:

"PREMIUM High Speed HDMI cable" or that + "with Ethernet" (up to 4K at 30Hz) --OR--

“ULTRA High Speed HDMI cable" or that + "48G" (supports higher resolutions and backward-compatible)

Cables with No Certification tags are good for your standard 720p TV set, and not much more.

Cables 'shipped in the box' with many displays can be "lowest bidder" cables that are not up to high-end display use. Cables with no markings 'found' behind your TV set are unlikely to be good enough.

HDMI was invented for HD TV sets. it works great at its original resolution of 720i or 720p. At higher resolutions, it quickly develops issues that are complex to solve, and the cables and adapters required to solve are NOT intuitive.

Higher and higher resolutions for displays are a step function, each protocol uses discrete steps at which it it willing to send its data.

We would all expect these to be Continuous functions, but with HDMI 1.4, the data rates supported peter out at 4K at 10 bits color.

HDMI 1.4 can only get there at 8 bits/color and 30 Hz without dropping display color quality. Starting from a USB-C port does not improve the situation, because there is no HDMI 1.4 step to support the data rates needed.

your Dell monitor U2723QE appears to be a 4K display capable of up to 10 bits/color and refresh rates of 23 to 87 Hz.

interfaces include:

HDMI 2.0. -- which, with higher spec cables should work FINE

DisplayPort 1.4

USB-C (DisplayPort 1.4 Alt Mode) with optional Power delivery for a laptop, if desired.

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A direct HDMI 2.0 connection will work with a PREMIUM or ULTRA certified Cable on your Mac Studio (but only 2023 or later).

It avoids the discontinuity in the HDMI 1.4 spec by using a higher speed DIRECT HDMI 2.0 input (still hits it when converting from USB-C to HDMI)

works on your older Macs because they are outputting 8 bits/color.

NB>> displays are not wired to the FRONT USB-C ports on most Mac Studio models -- they are considered data only.

Hi Grant, thanks for your reply. I’m using a 2m “High Speed HDMI cable with Ethernet”. I have done the following testing:

1. Connected the monitor to my 2017 “trash can” Mac Pro with this and two other HDMI cables —> no success
2. Connected the monitor to my 2017 “trash can” Mac Pro with the HDMI cable connected to an HDMI-mini DisplayPort adapter —> no success
3. Connected the monitor to my 2017 “trash can” Mac Pro with a DisplayPort – mini DisplayPort cable —> monitor works
4. Connected the monitor to my 2010 MacBook Pro with both a DisplayPort – mini DisplayPort cable and an HDMI cable with a mini DisplayPort adapter —> monitor works on both these connections
5. Attempted to daisy chain the monitor to my second Dell monitor (which was connected to my Mac Studio) using the DisplayPort – mini DisplayPort cable —> both monitors went dark.
6. Connected the monitor to my Mac Studio using the HDMI cable fitted with an HDMI–USB-C adapter —> no success.
7. Connected my Mac Studio to the second (newer) Dell monitor using the HDMI cable —> second monitor works.

I also have separately tested my second (newer) Dell monitor (a 4K U2723QE) to all three machines (Mac Studio, 2017 Mac Pro and 2010 MacBook Pro) using HDMI and HDMI with DisplayPort adapter, and it works in all scenarios.

Given the HDMI port on my older Dell monitor seems to be the consistent problem source (only working when connected to my 16-year-old MacBook Pro), is it worth getting a USB-C to DisplayPort adapter so I can connect to my Mac Studio via the monitor’s DisplayPort instead of HDMI?

Hi Grant, thanks for your reply. I don’t think the refresh rate is the issue. Just a bit of background on this monitor. According to the user guide, it supports 3840x2160 at 30Hz HDMI, and indeed, I have been using it at 30 Hz over HDMI at 4K resolution since I purchased it in 2015, initially with my trash can Mac Pro, and more recently with my Intel Mac Pro 2019. It started to exhibit some intermittent sleep/wake issues about a year ago (when connected via HDMI to my Intel Mac Pro). These issues continued and intensified after I connected it to my new Mac Studio. On the morning after the Mac Studio updated itself to OS27.2, the monitor would not display an image (possibly coincidental, but suspicious).

Thank you this is excellent advice – I will experiment with this set up.

Thanks, I will upgrade my HDMI cabling as well as experimenting with the DisplayPort adapter.