How to tell if a USB-C cable is Thunderbolt
Every guide says look for the lightning bolt. Most cables don't have one. Three ways to find out what a USB-C cable really is, in order of how much they actually tell you.
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WhatCable Field Notes
What the connector doesn't tell you.
Practical guides, protocol deep dives and findings from real Apple hardware. We explain what negotiated, what limited the connection and how to prove it.
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Latest field notes
Guides and deep dives
WhatCable doesn't just take the cable's word for it
The reviews are right that some cables lie. What they miss is that WhatCable checks the cable's claim against what the connection actually did, and against a second, independent hardware measurement. It diagnoses the whole chain, not the cable's own boast.
Thunderbolt vs USB-C: what the connector hides
USB-C is the connector. Thunderbolt is one of the protocols that runs through it. Here's what actually changes between TB3, TB4, USB4, and TB5.
From the archive
See what your own connection is doing.
WhatCable reads the port, cable, charger and connected device, then explains the result in plain English.