BenQ SW321C monitor won't connect to M3 Ultra

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BenQ SW321C monitor won't connect to M3 Ultra

BenQ SW321C monitor won't connect to new M3 Ultra. I have tried HDMI, USB-C cables, tried to use BenQ firmware update but their DisplayQuick firmware update software says "Unsupported Model". According to BenQ, the SW321C is a supported model and said there is a firmware update for my SW321C. Using ChatGPT I tried many restart, reconnect, detect displays, etc. but nothing worked. I ordered a USB-C to DisplayPort cable. I hope it works. I am using a two display set-up if that means anything. Any suggestions.

Mac Studio

Posted on Jan 15, 2026 5:30 AM

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Answer 1

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Servant of Cats

Level 8

46,407 points

Jan 16, 2026 12:35 AM in response to hoagie22

That monitor has

two HDMI v2.0 ports
one DisplayPort v1.4 port
one USB-C (DisplayPort Alt Mode, USB, PD) port
one USB-B upstream port
two USB 3.1 downstream ports

HDMI and DisplayPort do not carry USB data, so if you hooked up the monitor using only HDMI, or only DisplayPort, there wouldn't be a way to apply a firmware update to the monitor.

You would need either

A USB-C to USB-C connection, or
One of the other types of connection (HDMI or DisplayPort), plus a separate USB cable running from the USB-B port on the monitor to a USB-A or USB-C port on your Mac or on a hub/dock plugged into the Mac.

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Answer 2

hoagie22 Author

Level 1

5 points

Jan 16, 2026 3:09 AM in response to Servant of Cats

Thanks. I used a Maxonar Display Port to USB-C cable on my LG32UL950-W Display connected to the front Thunderbolt 5, left port, and for the BenQ SW321C-B display I used a Thunderbolt 4 Apple Pro cable on any of the rear Thunderbolt 5 ports. It appears the for the first time I have normal extended, two monitor display setup. I will work with this today but everything appears as expected for now.

The BenQ SW321C does not appear to work with Display Port or HDMI but the LG32UL950-W seems a lot more forgiving and connects using any of the cables.

We'll see how it goes, thank you for the help.

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BenQ SW321C monitor won't connect to M3 Ultra

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