I seem to have issues using external SSD’s ports 2/3 and 5/6. 3&6 might be because those ports are limited to low-power devices (0.9A), so I wanted to know if those of you who are using external SSD’s, what ports do you use and have you seen any issues with the ones I cited above? I like to leave 1&4 for power and hub connectivity, so I’d prefer not to use those.
I regularly use a Samsung SATA SSD (870 QVO) in an external enclosure plugged into a USB-A card in port 5 and a USB-A to USB-C cable and it has no problem with prolonged full speed writes. So I’d say power-wise it has no problem as I know when the SSD gets insufficient power it restarts and access operation hang.
I use port 1 and 4 for USB storage (nvme enclosures).
I use port 2 and 5 for PSU.
I have found that port 1 and 4 the most reliable for external SSDs.
It mainly comes down to power.
Some external SSDs need 9W of power.
According to this page:
“Ports 1,2,4,5 are shared on a first come first serve basis. So they are 1.5A by default, but one port from any of these can negotiate 3A over PD. Once that is taken, the other ports are limited to 1.5A. Ports 3,6 are 900mA.”
So, the 1.5A default (7.5W) is available on ports 1,2,4,5 with one of them winning and getting 15W. Thus only one capable of supplying enough power to the external SSD.
For NVME USB4 SSD enclosures, there is an nvme cli command that can limit their draw to less than 7.5W, that makes them more reliable, but a bit slower.
The NVME USB4 SSD enclosures I have a quite good with power, and only use 9W for very stort periods, so limiting the SSD to < 7.5W only limits those spikes and therefore improves stability, without much loss in performance.
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It’s interesting that port 5 would share that negotiation considering it’s on it’s own power rail, but perhaps that power rail is only relevant to incoming PSU power. Thanks for the info! I’ve been debating whether I should pickup a 8TB nvme to replace my internal or just use up the various 1 and 2TB drives I’ve got laying around. It sounds like I’ll only be able to use at most one of those drives at a time reliably. My enclosure is only 3.2, so there’s no performance hit to using ports 4/5 for me.
I’ve also had issues lately with my usbc wireless headset adapter disconnecting, I wonder how much power it’s pulling.