What is DisplayPort alt mode?
A mode where the USB-C cable carries a display signal directly, so one cable can charge a laptop and drive a monitor.
Power in, display out, data alongside, over one cable.
Rewiring the connector
Alternate mode reassigns some of the high-speed wires in a USB-C cable to carry a native DisplayPort signal instead of USB data. That is what makes a single-cable desk setup possible: power in one direction, video out in the other, data alongside.
Everything in the chain has to agree
It has to be supported by the source device, the cable and the display. A charging-only cable will not do it, and neither will many cheap data cables, because the wires that carry the display signal are the ones manufacturers leave out to save cost.
The resolution ceiling
The resolution ceiling depends on the generation. Where a maker publishes it, we record it as a maximum display figure rather than a vague claim of 4K support.
Cables we track that carry video
Full side-by-side on the cable ruler.