The A-to-A Cable: A Rare Connection With Narrow Uses
A USB 3.0 male to male cable has the same plug on both ends, usually Type-A to Type-A. That shape suggests it can link two computers, but the USB specification forbids a direct host-to-host connection. The cable does exist for a narrow set of legitimate uses, and buying the wrong one wastes budget and creates support tickets. Understanding which side is the host prevents the most common mistake.
Quick Answer / Summary
A USB 3.0 male to male cable with Type-A ends on both sides is an A-to-A assembly. It is not a host-to-host cable and must not connect two computers directly, because both hosts drive the bus and neither yields. Valid uses are limited to embedded targets and KVM or switch hardware that expects an upstream A-to-A link. For two computers, use a network or bridge solution instead.
What a USB 3.0 Male to Male Cable Actually Is
Male to male means both ends carry a plug. In the USB world, the connector type also signals direction. Type-A is the host-side shape, while Type-B and its variants are device-side shapes. Two Type-A plugs on one cable break that convention. Because both ends look identical, an A-to-A cable cannot indicate which side should be the host, which is why the design is uncommon in consumer products and confined to documented hardware.
A-to-A vs A-to-B
A-to-B is the standard host-to-device cable: the A end goes to the computer and the B end to the printer or dock. A-to-A pairs two host-side plugs, which is why it is unusual and easy to misuse.
Why Host-to-Host Connections Are Prohibited
USB is designed around one host that owns the bus and enumerates devices. Two hosts connected by a plain A-to-A cable both try to act as the controller, and both provide power. The result can be contention, enumeration failure, or damage to the ports. A compliant transfer between two computers therefore requires a controller that manages both sides, which a plain cable does not provide.
What Happens If You Connect Two Hosts
Neither side receives a valid device handshake, so no link forms. Current can flow from one host into the other, which some controllers protect against and others do not. It is never the intended method for transferring files.
Valid Uses: Embedded Targets and KVM Links
Some embedded boards expose an upstream Type-A port so the board acts as a device to a host PC. KVM switches and similar hardware can also present an A-to-A port because the switch is the controller, not a peer computer. In those cases the A-to-A cable is correct and documented by the vendor. Always follow the hardware documentation before buying an A-to-A assembly, because a generic replacement may not match the switching behavior the device expects.
What to Buy Instead for Two Computers
To move data between two computers, use a network link or a dedicated bridge device that represents itself properly to each host. A standard USB 3.0 A-to-B cable then connects each computer to a real peripheral, such as an external drive, and the data moves through that peripheral. These methods move files through a device that both hosts can talk to safely, which is the pattern USB was built around.
- Use a network cable for computer-to-computer transfers.
- Use a bridge device with proper host and device roles.
- Use a standard A-to-B cable only for host-to-peripheral links.
Comparison Table
| Cable type | Connects | Host-to-host |
|---|---|---|
| A-to-B | Host to device | Not applicable |
| A-to-A | Host to host or target | Only with a supported target |
| A-to-Micro-B | Host to device | Not applicable |
| Type-C to Type-C | Depends on both ports | Only with bridge hardware |
Table: Connector pairings and host-to-host support
Practical Application Scenarios
- A developer connects an embedded development board to a PC with the A-to-A cable the board vendor supplied, because the board presents itself as a device.
- An IT team sets up a KVM switch that lists an upstream Type-A port, so a USB 3.0 male to male cable links the switch to the server.
- A user tries to link two laptops with an A-to-A cable and gets no connection, then switches to a network cable.
- A technician keeps A-to-B cables on hand for printers and docks and reserves the A-to-A assembly for the KVM rack.
Related Products and Further Reading
- USB cable products – Compare A-to-B, Micro-B, and Type-C assemblies instead of a host-to-host pairing.
- contact our engineering team – Ask which connector pair fits your host and device roles before ordering.
- frequently asked questions – Answers common questions about connector types and cable selection.
- USB 3.0 A to B cable guide – Details the standard host-to-device cable that most setups actually require.
Frequently Asked Questions
Can a USB 3.0 male to male cable connect two computers?
No. Two hosts cannot form a USB link directly. Use a network connection or a bridge device designed for host-to-host transfer.
What is an A-to-A USB cable used for?
It is used where a device port is physically Type-A, such as some embedded boards and KVM switches. In those cases the hardware documentation specifies an A-to-A cable.
Will an A-to-A cable damage my computer?
It can. Both hosts provide power and port protection varies. Do not connect two computers with a plain A-to-A cable.
What cable should I use to connect a computer to a printer?
Use a standard A-to-B cable, where the A end goes to the computer and the B end to the printer.