Refers to AMD's family of 64-bit CPUs, which includes the Opteron for servers and high-end workstations, the Athlon 64 and 64 FX for desktops and the Mobile Athlon 64 and Turion 64 for laptops.

The AMD64 design, known as the Direct Connect Architecture (DCA), includes a set of 64-bit instructions as well as 64-bit registers that allows the CPU to address more than 4GB of memory, which is the limit of 32-bit registers. It also added a DDR memory controller directly on the CPU chip for increased performance. See Opteron, Athlon, Turion and AMD64 sockets.