Built-in HDMI Port Not Detected on MacBook Pro M4 Pro (Works via HDMI Hub)

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samanshakya Author

Level 1

4 points

Built-in HDMI Port Not Detected on MacBook Pro M4 Pro (Works via HDMI Hub)

Hello,

I recently noticed that the built-in HDMI port on my M4 MacBook Pro is not working. Here’s the situation:

When I connect my DELL S2721HN monitor directly to the built-in HDMI port, the monitor shows “Scanning signal… No HDMI signal” and goes into standby.
System Report → Graphics/Displays only shows the internal display; the external monitor is not detected at all.
The same monitor and HDMI cable work perfectly when connected via an HDMI hub.
I am running macOS Sequoia 15.6.1 (24G90) with the latest updates.
I have restarted the Mac multiple times, and macOS settings have been verified.
It seems that the HDMI port is not sending any signal, even though the GPU is functioning correctly,

Has anyone experienced this issue? Could this indicate a hardware fault with the HDMI port?

Thank you for any advice.

Specifications:

Macbook Pro M4 Pro Chip, 14 inch Nov 2024

24 GB RAM/512 GB SSD

macOS Sequoia 15.6.1 (24G90)

MacBook Pro 14″, macOS 15.6

Posted on Sep 10, 2025 10:53 PM

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Answer 1

Sep 11, 2025 06:27 AM in response to samanshakya

How are you connecting to the hub? Worth noting that Macs are sensitive to cable quality so if you're using a 'generic' HDMI cable that you borrowed from behind a TV that may be the cause. The hub may be less sensitive to the issue, assuming the hub is connected to a Thunderbolt port. As my colleague, Grant Bennet-Alder, frequently advises the cable should be labeled with Premium or Ultra for use with the Mac's HDMI port.

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Answer 2

Sep 11, 2025 06:58 AM in response to samanshakya

that DELL S2721HN display appears to be a 1920 by 1080 display with 8 bits/color and refresh up to 75 Hz.

interfaces include 2x HDMI 1.4

Mac Pro M4 has an HDMI port capable of HDMI 2.1, which can run much higher resolutions, but requires high spec cables. if you use cables that are not good enough, Transmit errors can occur, and the Mac will refuse to connect.

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.

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.

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