How much difference does the USB cable make to my SSD speed?

There are 3 categories of USB-C cable:

• A charging cable
• A data cable
• A thunderbolt cable

Here are some speed tests of an external Samsung T5 drive with 3 different cables.

A cheap ($10) charging-only cable.

~40 MB/s

Clearly the slowest of the cables. 1/10 the speed of a proper USB-C cable.

A USB-C charging + data cable ($25).

~400MB/s

A standard USB-C cable can achieve fast USB transfer speeds for an external hard drive. This cable was marketed as ‘USB-2 data speeds up to 480Mbps’ These cables can still be called ‘charging cables’ make sure they say they are USB-2 standard which means 480Mbps data rate.

Apple Thunderbolt 5 cable ($115)

~400MB/s

The fastest cable avaialble, Apple’s thunderbolt 5, is no faster here because the External Samsung drive is only capable of USBC-2 speeds.

A Thunderbolt cable is only of use when the external device (a storage device, graphics capture card, or another macboook) also has a thunderbolt port.

CONCLUSION: If you are just hooking up an external USB drive, there’s no added speed benefit from having a thunderbolt cable.