USB-C in 2026: Why Two Identical Cables Can Differ 100x in Speed, What USB4, Thunderbolt 5 and 240 W Charging Actually Mean, and How to Buy the Right One
- Equipo de Internet Pros
- September 29, 2026
- Redes y Seguridad
Este artículo está disponible solo en inglés.
Pick up two USB-C cables from any office drawer. They have the same oval plug, and they probably look almost identical. One may move data at 480 megabits per second, the speed of a 2001 flash drive. The other may carry 80 gigabits per second, more than 160 times faster, plus two 4K monitors and enough power to charge a workstation laptop. Since 28 April 2026 the EU has required new laptops sold there to charge over USB-C, which completes the single-connector world the industry promised a decade ago. The connector has been standardised. What travels through it has not, and that gap costs businesses slow backups, flickering docks and laptops that refuse to charge.
The Plug Is Not the Protocol
USB-C describes only the shape of the connector and the wires inside it. What actually runs over those wires is negotiated between the two devices and depends on three separate things:
- The data standard both ends support: USB 2.0, USB 3.2, USB4 or Thunderbolt.
- The power standard: basic 5 V USB power, or USB Power Delivery (PD) negotiating up to 240 W.
- The cable itself, which may be missing the high-speed wire pairs completely or may carry a tiny chip, called an e-marker, that tells the devices what it can safely handle.
The link runs at the lowest level all three support. A Thunderbolt 5 laptop plugged into a Thunderbolt 5 dock through the cheap cable that came with a phone gets USB 2.0 speeds, and usually no error message at all.
USB-C standardised the hole in the side of the laptop. It did not standardise what comes out of it.
Decoding the Data Speeds
Version names made this worse. USB 3.0 was renamed USB 3.1 Gen 1 and then USB 3.2 Gen 1, all for the same 5 Gbps. The USB Implementers Forum (USB-IF) has since told manufacturers to put the speed on the box instead, and its current logos simply say “USB 10Gbps” or “USB 80Gbps”. Here is how the names line up:
| Marketing label | Technical name | What it is good for |
|---|---|---|
| USB 480Mbps | USB 2.0 (common on charging cables) | Keyboards, mice, charging. Painful for files. |
| USB 5Gbps / 10Gbps | USB 3.2 Gen 1 / Gen 2 | External SSDs, basic single-monitor docks |
| USB 20Gbps | USB 3.2 Gen 2x2 or USB4 20Gbps | Fast portable SSDs (rarely supported by Macs) |
| USB 40Gbps | USB4 40Gbps, Thunderbolt 3 and 4 | Docks driving two displays, external GPUs, 10 GbE adapters |
| USB 80Gbps | USB4 Version 2.0, Thunderbolt 5 | Multiple high-refresh or 8K displays, video editing off fast storage |
One useful detail: USB4 Version 2.0 was designed to reach 80 Gbps over existing certified 40 Gbps passive cables, so a good cable bought in 2023 is not automatically obsolete.
USB4 Versus Thunderbolt: Minimums Matter
Thunderbolt 4 and 5 are built on the USB4 specification, so the two usually work together. The real difference is what is guaranteed. Many USB4 features, such as PCIe tunnelling for external storage and graphics or support for two displays, are optional. A laptop can print USB4 on its spec sheet and still leave out the feature your dock needs.
Intel’s Thunderbolt certification turns those options into requirements. Thunderbolt 5 guarantees 80 Gbps in both directions, a Bandwidth Boost mode that sends up to 120 Gbps toward displays, support for multiple 4K and higher displays, and laptops that accept at least 140 W of charging. For a fleet of business laptops paired with shared hot-desk docks, that predictability is often worth more than the headline speed.
Speed also changes the cable length you can use. At 40 and 80 Gbps a passive copper cable reaches only about a metre, so a dock on a shelf or a monitor across the room needs an active or optical cable.
Power Delivery: From 60 W to 240 W
USB Power Delivery lets a charger and a device agree on a voltage before any real current flows. The original Standard Power Range tops out at 20 V and 5 A, or 100 W. USB PD 3.1 added the Extended Power Range, with fixed 28, 36 and 48 V levels, and 48 V at 5 A is where the 240 W figure comes from. That is enough for gaming laptops, monitors and some small power tools.
The cable limits all of this. Any USB-C to USB-C cable must handle 3 A, which means 60 W at 20 V. Anything above 3 A needs an e-marked 5 A cable, and 240 W needs a cable certified for Extended Power Range. Plug a 140 W laptop into a 60 W cable and it will charge slowly, or not at all while it is under heavy load.
Chargers have shrunk too. Gallium nitride transistors, covered in our guide to wide-bandgap semiconductors, let a 100 W multi-port charger fit in a jacket pocket. Keep in mind that the rating on a multi-port brick is usually shared between its ports, so a 100 W charger does not deliver 100 W to each of them.
The EU Common Charger Rule, Now Including Laptops
The EU Radio Equipment Directive amendment applied to phones, tablets, cameras, headphones and similar devices from 28 December 2024. Laptops followed on 28 April 2026. Covered devices must have a USB-C charging port, must support USB Power Delivery if they charge above 15 W, and must be sold with an option that leaves the charger out of the box.
The rule only applies within the EU, but manufacturers rarely build a separate version for other markets, so the effect is worldwide. For IT buyers this means fewer proprietary barrel chargers, spare power bricks that work across brands, and a growing pile of old chargers to recycle, a trend our piece on digital product passports follows further.
Where It Still Goes Wrong
- Ports that differ on the same laptop. Often only one side supports display output or full-speed charging. Look for the small icons next to the port, or check the manual.
- The DisplayLink versus Alt Mode confusion. Some docks send video as compressed USB data and need a driver. Others use DisplayPort Alt Mode natively. Macs with base-model chips often support fewer external displays than the dock box suggests.
- Uncertified cables. A cable that falsely reports 5 A support, or cheap cables with no e-marker at all, can overheat or trigger charging faults. Buy certified cables from reputable brands.
- Silent downgrades. Windows 11 may warn you when a cable or port limits a USB4 connection, but most devices simply fall back to a slower mode without telling you.
A USB-C Buying Checklist for Offices
- Buy cables by label, not by look. Choose USB-IF certified cables marked with both a speed and a wattage, for example “80Gbps / 240W”, for anything that connects to a dock.
- Colour-code or tag them. Put a coloured band on high-speed cables so charging-only cables never end up on a dock.
- Standardise the dock and laptop together. Thunderbolt certified on both ends removes most of the guesswork on shared desks.
- Match charger wattage to the heaviest laptop. Then confirm the cable is rated for at least that much current.
- Keep cables short. Use passive cables of a metre or less for high-speed links, and active or optical cables beyond that.
En resumen
USB-C finally delivered one connector for everything, from phones to AI laptops and 8K monitors. The price of that convenience is that you can no longer tell a cable’s speed or power rating by looking at it. Read the speed and wattage on the label, give Thunderbolt certification priority where docks are shared, and treat the cables themselves as specified equipment rather than accessories. Most “my dock is broken” help-desk tickets turn out to be a cable problem.
Rolling out new laptops or hot desks? Talk to Internet Pros. We specify matching laptops, docks, chargers and cables, and set up workspaces where everything connects at full speed the first time.
