Max number of USB device - power limitation

[tony359]

Hi there,

I have normally 2 USB-C devices plugged in my Mac Mini M4. One is a USB-4 SSD enclosure with an nVme drive in it. The other one is a powered Targus dock (10Gbps) where many other devices are plugged in, including two extra monitors via DisplayLink. A third monitor is directly connected to the HDMI output. Resolution is 1440p. I'm using the ports at the back.

I wanted to get rid of the DisplayLink driver (it can be taxing) so I bought two USB-C to HDMI dongles from Cable Matters.

Unfortunately, with those plugged in and working, the SSD refuses to work.

I've had a look online and I've learnt that there is a power budget for those ports and I've learnt that Apple might not deliver the full budget required by the specs.

I'm just puzzled that two USB-C to HDMI dongles can break the power budget for the mini.

Do you think there is a workaround for this issue (maybe my dongles draw too much power?) or not?

I'd imagine a powered USB enclosure might help?

 

[throAU]

Yes, if you're plugging in multiple things into a USB hub you should probably make sure it is powered.

This isn't just a Mac thing, any machine with USB ports has a limited power budget on each port.

 

[tony359]

The hub is powered. That is not my issue. The issue does not involve the hub 🙂

The SSD refuses to work with the following devices plugged in at the back:
2 x HDMI dongles
1 x USB SSD

Also, there seems to be a total budget as I can have 2 of those devices working - just not all three simultaneously.

BTW, Just tested the same configuration (2 x HDMI dongles + USB SSD) on an M1 Max MBP and it works with zero issues.

I'm disappointed Apple doesn't post clearer specs so one can make an educated decision when purchasing accessories.