MacBook Pro M5 Max external display drops via dock

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stevieh59 Author

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9 points

MacBook Pro M5 Max external display drops via dock

Purchased a MacBook Pro M5 Max and it doesn't seem able to hold the connection to a BenQ monitor through my doc.

Shows on external, then display reverts back to own screen, then back to external display and repeat

Weirdly I have a MacBook Pro M2 Max and this connects fine through the exact same, connections, dock and monitor.

Dock

UGREEN Revodok Max Thunderbolt 5 Dock, 13 Ports TB5 Docking Station

Monitor

BENQ DesignVue PD3205U 4K Ultra HD 32" IPS Monitor

Cable (to get to the monitor from dock)

JSAUX USB C to HDMI Cable 3M【4K@60Hz】 USB 3.1 Type-C to HDMI 2.0 Cable for Home Office, (Thunderbolt 3/4 Compatible)

https://www.amazon.co.uk/dp/B07XCTP2K9?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1

Connection from MacBook Pro to Dock is with the supplied cable from UGREEN,

Out of the MacBook into monitor is as above

Also run a 2019 iMac into the same monitor via USBc to Display port. the M5 is fine here

Posted on Jun 6, 2026 9:22 AM

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Answer 1

Jun 6, 2026 1:50 PM in response to stevieh59

BENQ DesignVue PD3205U 4K Ultra HD 32" IPS Monitor appears to be a 3840 by 20160 (4K) display with 10 bits/color HDR capability capable of up to 60 Hz.

Interfaces include:

HDMI 2.0

DisplayPort 1.4

USB-C with power delivery

Both HDMI and DisplayPort (used inside Thunderbolt and USB-C) are packet interfaces. In each case, the interface runs at one of a few Fixed speeds, and if there is LESS data than fully fills every packet at that speed, then packets are (generally) omitted, or stuffed with null data.

You can not run combinations of resolution, bits/color, AND refresh rate that exceed the top speed of the pathway provided. If the display supports Display Stream Compression (DSC) [mostly DisplayPort displays], you can get slightly higher data rates (seen as combinations of resolution, bits/color, and refresh rate).

When adapting display data from USB-C, each display interface uses a different set standard speeds, as part of their standards. Each allowed speed must fit inside the maximum speed of USB-C, which is 20 G bits sec.

for HDMI, the highest standard speed that can be supported by the protocol is 14.4 G Bits/sec. That allows a 10 bits/color 4K HDR display to run at up to 50 Hz. IF your display supports a slightly different reduced color space, it MIGHT be able to run as fast as 60 Hz in a reduced color space under ideal conditions.

for DisplayPort, the highest standard speed that can be supported by the protocol is 17.28 G Bits/sec HBR2. That allows a 10 bits/color 4K HDR display to run directly at up to 60 Hz. If your display supports a Display Stream Compression as well, it should be able to run as fast as 180 Hz, but the number of colors may begin to suffer as more compression is applied.

>> Use an adapter from USB-C to DisplayPort for higher resolutions and faster refresh rates.

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Answer 2

Jun 6, 2026 1:53 PM in response to stevieh59

<< Cable (to get to the monitor from dock)

JSAUX USB C to HDMI Cable 3M【4K@60Hz】 USB 3.1 Type-C to HDMI 2.0 Cable for Home Office, (Thunderbolt 3/4 Compatible)

https://www.amazon.co.uk/dp/B07XCTP2K9?ref=ppx_yo2ov_dt_b_fed_asin_title&th=1. >>

You can indeed attain 4K at 60 Hz with that cable... However, that is ONLY at 8 bitsscolor, not at the full 10 bits/color both your Mac and display can provide.

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