What is an e-marker chip in a USB-C cable?
A small chip that tells the charger what the cable can carry. Without it the link is capped at 3 A, 60 W.
The charger asks the cable what it can take. No chip, no conversation.
A chip that speaks for the cable
Every USB-C cable that claims more than 60 W has to contain an electronically marked identity chip, an e-marker. When you plug in, the charger interrogates that chip and learns the cable's current rating, its data speed and whether it supports the EPR voltages.
The silent 60 W ceiling
If there is no e-marker, the specification requires the charger to assume the cable is a 3 amp, 60 watt part, and it will not offer anything more. This is the single most common reason people see slow charging with an expensive charger: the charger is fine, the phone is fine, and the unmarked cable in the drawer is quietly holding both back.
You cannot see it from outside
You cannot see an e-marker from the outside. The reliable signal is the printed wattage rating and, better, USB-IF certification.
a 100 W laptop charger delivering 60 W with no error message anywhere.
any cable printed 100 W or 240 W. Length barely matters for charging; the rating does.
Cables we track with an e-marker
Full side-by-side on the cable ruler.