12-28-2018 11:44 AM
I ran a speed test on my new T480's USB-C port on an external SSD. I am using a Sabernet SSD external enclosure with a USB-C adapter. Inside is a m.2 SSD (not NVMe). I also tested the same SSD with a USB 3.1 adapter and the speeds are MUCH faster on the USB 3.1 than the USB-C port. I can post screenshots of CrystalDisk if needed. Any advise?
12-28-2018 12:11 PM - edited 12-28-2018 12:12 PM
Out of curiosity, when you say: "adapter," what do you mean? It is a whole new cable with the A and C heads? Or is it just a small block where you plug the existing USB-C cable into?
The reason why I ask? Is it possible the USB-C cable is actually USB 2.0 spec (like a USB-C "charging cable").
Of course, if you are using the same USB-C cable in both instances, then I do not know what to do. There are two USB-C ports on your T480, maybe try plugging it into the other one?
12-28-2018 12:23 PM - edited 12-28-2018 12:25 PM
Here are the parts. Theoretically, the USB-C (which is USB 3.1) should be faster (or at least the same speed) as the USB 3.0. Am I correct?
I am using a ZTC 256GB Armor 42mm M.2 NGFF 6G SSD.
This is the enclosure, Sabrent M.2 SSD to 2.5-Inch SATA III.
These 2 adapters for the enclosure.
Sabrent USB 3.0 to SSD
And the Sabrent USB 3.1 Type C to SSD
*Edit: I am planning on using this for a few Virtual Machines.
12-28-2018 02:58 PM
This is weird.
There should be no speed difference between the two. SATA is limited to 600MB/s and both 5Gb (USB3.0) and 10Gb (USB3.1) have plenty of bandwidth for this.
I have no idea why it is slower on the USB-c though. Have you tried booting from a Linux Live USB stick to do benchmars (Gnome Disks) in Linux in case there is a software issue in Windows?
12-28-2018 10:38 PM - edited 12-28-2018 10:47 PM
One way to find out is to use an USBC --> USB-A adapter and plug the USB-C version into an USB-A port. The reasoning for this guess is:
The USB-C ports on this laptop should be driven from the TB3 chip (USB 3.1 gen2), wheras the USB-A ports (USB 3.1 gen1 née USB 3.0) should be driven directly from the PCH (one less layer, since the TB3 chip is connected to the PCH via PCIe). Maybe the USB-C ports have less performance? Maybe the USB-C version of the adaptor is less capable? It does advertise USB3.1gen2 speeds (10Gbps), which indicates to me there is some other HW difference in the adaptor (namely, one more high speed pair).
EDIT: that last part is wrong. 10Gbps only uses one pair, same as the older 5Gbps version.