I got two adapters that convert USB C to a SATA interface, you can bus power a SSD, so this is not a bad test. I then ran Black Magic Speed Test and found to my surprise that one of the cables is 20-30% faster than the other. I used two SSDs, a Toshiba OCZ TR150 1TB and a Samsung 850 EVO 1TB and as expected the 850 EVO was slightly faster.
- Sabrent 2.5″ SATA Hard Drive/SSD to USB Type-C Adapter EC-HDSS. This cable’s main drawback is that it is long (about 0.5meters long), but it has an LED to tell you it is operating and both of these drives averages 510MBps read and 480MBps write on this interface. It also says it supports UASP so should be good for small reads and writes. At $17, it is hard to lose
- Cable Matters USB C to SATA. I don’t have the exact part number for this, but it’s main advantage is that it has a much shorter cable, probably about 0.25 meters. However is is slower for both these drivers running at 400MBps read and 380MBps for the Evo and 360MBps read and write for the OCZ. Not sure that makes a huge difference, but I use these for big backups, so it does save time. One reviewer by the way says it’s not compatible with the MacBook Pro late 2016, I haven’t found this to be a problem at least on my 15″ MBP.
- Startech USB 3.1 Adapter Cable for SATA with USB C. I also have ordered this but haven’t tested it yet.