What "USB4" does and doesn't promise
USB4 version 1 identifies two transfer rates, 20Gbps and 40Gbps. The USB4 Version 2.0 spec adds the 80Gbps tier. The USB Promoter Group released it on 18 October 2022. USB-IF's own overview says the standard supports up to 80 Gbps operation over 80 Gbps certified cables. It adds that the resulting connection scales to the best mutual capability of the devices being connected.
In practice, "supports USB4" can mean any of three speeds. Two laptops can both advertise USB4 and behave very differently on the same drive.
The 120Gbps figure needs care. MakeUseOf describes it as an optional asymmetric mode. It sends 120Gbps one way and keeps 40Gbps in the other direction, so it is aimed at displays rather than file copies. Don't treat 120Gbps as a storage speed.
The naming fix that hasn't fully landed
USB-IF's current guidance recommends speed-based consumer names. The USB4 and USB 3.2 specifications together identify five transfer rates: 80, 40, 20, 10 and 5Gbps. Vendors are expected to clearly communicate the signaling a product delivers in packaging, advertising and other marketing.
The recommended names are "USB 20Gbps", "USB 40Gbps" and "USB 80Gbps". Terms like USB4 Version 2.0 and USB 3.2 Gen 2x2 are meant to stay off consumer packaging. One guide quoting the guidelines says the five consumer names are USB 5Gbps through USB 80Gbps.
The catch is that spec sheets don't always follow the guidance. MakeUseOf notes that plenty of listings still say only "USB4" or "USB-C". The guidance recommends compliance testing and logos but doesn't force a speed label onto every port. I found nothing in the reviewed sources that requires a printed speed beside each host port.
USB4 versus Thunderbolt labels
Thunderbolt is the more predictable label because Intel certification enforces minimums. MakeUseOf's comparison table, attributed to Intel's requirements, lists these:
| Label | Link speed | Certified minimums (per MakeUseOf) |
|---|---|---|
| USB4, no speed label | 20Gbps guaranteed, 40Gbps optional | 10Gbps USB 3.2 data, no display minimum |
| USB4 40Gbps | 40Gbps | Same data and display baseline |
| Thunderbolt 4 | 40Gbps | 32Gbps PCIe, two 4K displays, up to 100W charging on at least one PC port |
| USB4 80Gbps | 80Gbps, with the 80Gbps logo | Nothing beyond the speed label |
| Thunderbolt 5 | 80Gbps, up to 120Gbps boost | 64Gbps PCIe, dual 6K displays, up to 140W on at least one PC port |
The two systems are related but not interchangeable. USB-IF says USB4 is based on the Thunderbolt protocol specification contributed by Intel. That shared lineage doesn't make a USB4 port a Thunderbolt port.
The cable is half the story
Cables carry their own speed rating, and it is separate from their power rating. A 240W cable isn't automatically an 80Gbps cable. USB-IF logos on cables show speed and power together, for example 40Gbps/240W.
The cable also takes part in the negotiation. One cable guide reports that a USB 2.0 cable limits any device to 480 Mbps. The same guide says USB4 mode won't activate without an e-marker response. The host then falls back to ordinary USB. That guide is a secondary source, but its description is consistent with USB-IF's statement that 80Gbps requires certified cables.
There is some nuance. One secondary guide says USB4 Version 2.0 can reach 80Gbps over existing 40Gbps passive cables and newly defined 80Gbps active cables. That means cable requirements depend on the configuration. The safest buying rule is to match the cable's printed speed logo to the port and device.
How to check your own setup on Windows 11
- Read the manufacturer's spec page for your exact model. Skip the retailer listing. Look for an explicit 20, 40 or 80Gbps figure. If it says only "USB4", MakeUseOf advises assuming the lower tier. That is a cautious rule of thumb, not a standards guarantee.
- Open the Windows USB4 page. Starting in Windows 11 build 22621.1778 (KB5026446), Settings lists attached USB4 hubs and devices and their capabilities. The path is Settings > Bluetooth & devices > USB > USB4 Hubs and Devices.
- Don't panic if the page is missing. Microsoft says a system that isn't USB4-capable won't show it. Microsoft also says that if the host router is only enumerated when a USB4 device is attached, the page may stay hidden until then. In that case OEMs are advised to set a registry value so the page is always visible. That is an OEM matter, not something to hand-edit on a work machine.
- Check the cable's data rating. Look for a speed logo, not just a wattage.
- Check the drive and any dock in the chain. The link follows the best mutual capability, so a 20Gbps enclosure caps the connection at 20Gbps. MakeUseOf makes the same point.
- Run a real copy test as a hint, not proof. MakeUseOf says a drive rated for several gigabytes per second that tops out near 400MB/s behaves like a 5Gbps connection. That is the author's observation. Real copy speeds also depend on the drive, file sizes and caching, so treat it as a clue and confirm with the other checks.
The Windows page reports detected USB4 hubs and devices and their capabilities. It isn't a universal speed meter for every USB-C port, and it doesn't prove a given cable is carrying its theoretical maximum.
Do you need 80Gbps?
Probably not for a mouse, keyboard, flash drive or ordinary SSD, as the MakeUseOf author notes. The extra bandwidth matters for docks that carry two high-resolution displays plus fast storage, for external GPU enclosures, and for editing video directly off a fast NVMe drive. For those uses, it's worth paying for a port, cable and device that all clearly state 40Gbps or 80Gbps.
Bottom line
"USB4" tells you the protocol family, not the speed. Treat an unlabeled USB4 port as the lowest tier until the manufacturer says otherwise. Buy by speed logo rather than version number, and keep cable speed and cable wattage as two separate questions. Windows 11's USB4 page helps you confirm what is attached, but the spec sheet and the cable markings still do most of the work.