Which company owns MAC address prefix 40:8D:5C?

MAC address prefix 40:8D:5C is registered to GIGA-BYTE TECHNOLOGY CO.,LTD. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:8D:5C has a network interface built by GIGA-BYTE TECHNOLOGY CO.,LTD..

What is the OUI 40:8D:5C?

40:8D:5C is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to GIGA-BYTE TECHNOLOGY CO.,LTD.. It covers every address from 40:8D:5C:00:00:00 to 40:8D:5C:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-8D-5C.

How do I find the manufacturer of a MAC address?

Take the first three octets of the address — in 40:8D:5C:00:00:00 that is 40:8D:5C — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.

Where is GIGA-BYTE TECHNOLOGY CO.,LTD. located?

GIGA-BYTE TECHNOLOGY CO.,LTD. is listed at Pin-Jen City, Taoyuan, Taiwan, R.O.C. Pin-Jen Taoyuan TW 324 in the IEEE OUI registry entry for 40:8D:5C. This is the address the organization registered with the IEEE, which may differ from its current operating address.

How many MAC prefixes does GIGA-BYTE TECHNOLOGY CO.,LTD. own?

GIGA-BYTE TECHNOLOGY CO.,LTD. holds 21 OUI prefixes in the IEEE registry, of which 40:8D:5C is one. A device made by GIGA-BYTE TECHNOLOGY CO.,LTD. could carry a MAC address from any of them.

GIGA-BYTE TECHNOLOGY CO.,LTD.

MAC address prefix 40:8D:5C is registered to GIGA-BYTE TECHNOLOGY CO.,LTD. in the IEEE OUI registry. Any device whose MAC address begins with 40:8D:5C has a network interface built by GIGA-BYTE TECHNOLOGY CO.,LTD.. This prefix (the OUI, or Organizationally Unique Identifier) is assigned by the IEEE and is the first three octets of the address — it covers every MAC from 40:8D:5C:00:00:00 to 40:8D:5C:FF:FF:FF.

OUI prefix: 40:8D:5C
Hyphen form: 40-8D-5C
MAC range: 40:8D:5C:00:00:00 – 40:8D:5C:FF:FF:FF
Addresses in block: 16,777,216
Organization: GIGA-BYTE TECHNOLOGY CO.,LTD.
Address: Pin-Jen City, Taoyuan, Taiwan, R.O.C. Pin-Jen Taoyuan TW 324
Source: IEEE OUI registry

Have a full MAC address? Look it up— we'll also tell you if it's a randomized (private) address rather than a real manufacturer prefix.

Other prefixes from GIGA-BYTE TECHNOLOGY CO.,LTD.

GIGA-BYTE TECHNOLOGY CO.,LTD. holds 21 OUI prefixes in total. A device with this exact prefix could just as well carry any of these:

Assignment history (2)

The IEEE registry publishes current state only — this is the change record we've kept since we started tracking it daily.

2016-07-29Assigned to "GIGA-BYTE TECHNOLOGY CO.,LTD."
archived source →
2026-07-17Assigned to "GIGA-BYTE TECHNOLOGY CO.,LTD."

Nearby in the registry

The prefixes assigned immediately before and after 40:8D:5C:

FAQ

Which company owns MAC address prefix 40:8D:5C?: MAC address prefix 40:8D:5C is registered to GIGA-BYTE TECHNOLOGY CO.,LTD. in the IEEE Organizationally Unique Identifier (OUI) registry. Any device whose MAC address begins with 40:8D:5C has a network interface built by GIGA-BYTE TECHNOLOGY CO.,LTD..
What is the OUI 40:8D:5C?: 40:8D:5C is an Organizationally Unique Identifier — the first three octets (24 bits) of a MAC address, assigned by the IEEE to GIGA-BYTE TECHNOLOGY CO.,LTD.. It covers every address from 40:8D:5C:00:00:00 to 40:8D:5C:FF:FF:FF, or 16,777,216 addresses in total. It is also written 40-8D-5C.
How do I find the manufacturer of a MAC address?: Take the first three octets of the address — in 40:8D:5C:00:00:00 that is 40:8D:5C — and look that prefix up in the IEEE OUI registry. If the second-lowest bit of the first octet is set, the address is locally administered (a randomized or private MAC), which belongs to no manufacturer and will not resolve; modern phones and laptops use these by default on each network.
Where is GIGA-BYTE TECHNOLOGY CO.,LTD. located?: GIGA-BYTE TECHNOLOGY CO.,LTD. is listed at Pin-Jen City, Taoyuan, Taiwan, R.O.C. Pin-Jen Taoyuan TW 324 in the IEEE OUI registry entry for 40:8D:5C. This is the address the organization registered with the IEEE, which may differ from its current operating address.
How many MAC prefixes does GIGA-BYTE TECHNOLOGY CO.,LTD. own?: GIGA-BYTE TECHNOLOGY CO.,LTD. holds 21 OUI prefixes in the IEEE registry, of which 40:8D:5C is one. A device made by GIGA-BYTE TECHNOLOGY CO.,LTD. could carry a MAC address from any of them.