FIELD GUIDESource-led reference
Port & Cable

Capability library / usb

USB: transport, not just the plug

Read USB data capability, passive versus active cable scope and shared transport separately.

01 / READ THE QUALIFICATION

What the specification does—and does not—establish.

Published scope, conditions and what remains unknown. Figures are not measured end-to-end performance.
Name or markSupported reading and conditionsDo not inferAuthority
USB 2.0 Type-C cableUp to 480Mbps data; power marked separatelyRead the actual cable’s data specification.A power-only marking does not establish video or high-speed data.S511 · USB-IFChecked 2026-10-11
USB4 connectionShared multi-protocol transportIdentify the implemented version, both endpoints and dock path.The shell does not reveal traffic allocation or application speed.S522 · USB-IFChecked 2026-10-11
USB4 v2 / USB 80GbpsUp to 80Gbps qualified link operationCapable endpoints plus suitable passive or active cable.A prior active cable is not covered by the passive-reuse statement.S512 · USB-IFChecked 2026-10-11
USB4 asymmetric modeUp to 120Gbps one way; 40Gbps reverseOptional configuration for a supporting path.Not 120Gbps in both directions.S512 · USB-IFChecked 2026-10-11

USB 2.0 Type-C cable

Published scope
Up to 480Mbps data; power marked separately
Conditions
Read the actual cable’s data specification.
Do not infer
A power-only marking does not establish video or high-speed data.
Authority
S511 · USB-IF
Checked 2026-10-11

USB4 connection

Published scope
Shared multi-protocol transport
Conditions
Identify the implemented version, both endpoints and dock path.
Do not infer
The shell does not reveal traffic allocation or application speed.
Authority
S522 · USB-IF
Checked 2026-10-11

USB4 v2 / USB 80Gbps

Published scope
Up to 80Gbps qualified link operation
Conditions
Capable endpoints plus suitable passive or active cable.
Do not infer
A prior active cable is not covered by the passive-reuse statement.
Authority
S512 · USB-IF
Checked 2026-10-11

USB4 asymmetric mode

Published scope
Up to 120Gbps one way; 40Gbps reverse
Conditions
Optional configuration for a supporting path.
Do not infer
Not 120Gbps in both directions.
Authority
S512 · USB-IF
Checked 2026-10-11
An old cable is not one category. USB4 v2 source scope distinguishes passive from active. Passive 40Gbps: Explicitly included in the source. Older active cable: Needs its own qualification. Host and peer: Both must support the target mode. Actual result: Still a negotiated connection. Architecture support is not inspection of your cable.
Original concept diagram · not connector geometry, not to scale, not a certification mark. S512 · USB-IF

02 / FOLLOW THE ACTUAL PATH

4 cases. Three honest outcomes.

Supported under stated conditions, excluded within a stated scope, or not established. Only 4 cases belong to this desk; none is a universal compatibility approval.

Supported under stated conditions · not hardware tested

Can a passive 40Gbps cable serve a USB 80Gbps path?

USB-IF explicitly includes existing 40Gbps passive cables in its USB4 v2 architecture statement.

Still unknown. Actual cable condition and negotiated mode are unverified.

Next check. Confirm that the cable is passive and verify both port specifications.

Host, cable, destination, power and evidence
Host / source
USB4 v2 endpoint with the required mode.
Cable / intermediary
A genuine, suitable passive cable; not merely a sales label.
Destination / sink
USB4 v2 endpoint with matching support.
Power direction / supply
Charging remains a separate PD negotiation.

Basis: source-scoped interpretation. This classifies only the stated proposition, not an entire equipment pairing.

C034B

USB-IF describes USB4 v2 operation up to 80Gbps over existing 40Gbps passive Type-C cables or newly defined 80Gbps active cables.

Architecture-level statement; do not extend passive-cable reuse to every old active cable or unverified cable.

S512 · USB-IF

S512 · USB-IF

Not established · not hardware tested

Does an older active USB4 cable also support the new rate?

The passive-cable statement cannot be used to qualify an older active cable.

Still unknown. The selected active cable’s high-rate support is missing.

Next check. Obtain the active cable’s own data specification; do not copy a passive-cable conclusion.

Host, cable, destination, power and evidence
Host / source
Identify the newer host port mode.
Cable / intermediary
Exact active cable model and supported generations required.
Destination / sink
Identify the destination’s mode.
Power direction / supply
Read cable power separately.

Basis: source-scoped interpretation. This classifies only the stated proposition, not an entire equipment pairing.

C034B

USB-IF describes USB4 v2 operation up to 80Gbps over existing 40Gbps passive Type-C cables or newly defined 80Gbps active cables.

Architecture-level statement; do not extend passive-cable reuse to every old active cable or unverified cable.

S512 · USB-IF

S512 · USB-IF

Excluded in stated scope · not hardware tested

Does 120Gbps asymmetric mean 120Gbps each way?

No. The optional asymmetric configuration is 120Gbps in one direction and retains 40Gbps in reverse.

Still unknown. Application throughput and traffic allocation are not supplied.

Next check. State both directions when recording the link mode.

Host, cable, destination, power and evidence
Host / source
Host supports the optional asymmetric configuration.
Cable / intermediary
Suitable high-rate link cable.
Destination / sink
Peer supports the same configuration.
Power direction / supply
Independent of the link-allocation question.

Basis: source-scoped interpretation. This classifies only the stated proposition, not an entire equipment pairing.

C034C

The USB4 v2 announcement describes an optional asymmetric configuration: up to 120Gbps in one direction while retaining 40Gbps in the reverse direction.

Optional transport configuration, not symmetric throughput or a file-transfer guarantee.

S512 · USB-IF

S512 · USB-IF

Not established · not hardware tested

Will a USB4 dock deliver the full link rate to an SSD?

The connection’s transport figure is not a measured disk-transfer figure.

Still unknown. Shared display traffic, controller path and storage performance are missing.

Next check. Identify every stage rather than converting the headline link rate into a promised copy speed.

Host, cable, destination, power and evidence
Host / source
Exact host and storage transport support.
Cable / intermediary
Cable qualification plus dock upstream path.
Destination / sink
Exact SSD, enclosure and dock downstream port.
Power direction / supply
Use the dock and storage manufacturer’s power requirements.

Basis: source-scoped interpretation. This classifies only the stated proposition, not an entire equipment pairing.

C033B

USB-IF describes USB4 as a multi-protocol architecture whose common connection can carry different traffic types; capabilities depend on the connected products.

Architecture-level transport summary; application throughput and dock routing remain unspecified.

S522 · USB-IF

S522 · USB-IF

Continue to the permanent reference.

Earlier capability-library bookmarks remain available below; the table and cases above use the newer source-scoped observations.

Read a USB data-rate label literally

USB 3.2 nomenclature and modes →

Retained source-scoped study · 10 October 2026

A declared USB data rate describes a performance class, not the speed of every connected device. The link is bounded by both endpoints, the cable, the actual mode and workload overhead. Read USB 5Gbps, 10Gbps, 20Gbps, 40Gbps and 80Gbps as separate rate classes rather than a promise made by USB-C shape.

Label
A USB data-rate claim is not the same field as connector type.
Negotiation
Both ends need a mutually supported data mode.
Real throughput
Actual file-copy throughput is not equal to raw signaling rate.

Do not assume. Expecting a USB-C 240W charge cable to support 40Gbps merely because it carries high power.

  1. Confirm the computer port’s data mode and the accessory’s required USB mode.
  2. Look for an explicit USB data-performance label or a qualified cable model specification.
  3. Separate a signaling ceiling from measured application throughput.

S040 · USB-IF · S006 · USB-IF

Original study retained, not newly reinspected or independently approved. Its source-record dates and limits are unchanged.