A family of 64-bit CPU chips from AMD, formerly code named Sledgehammer (part of the Hammer line). Introduced in April 2003, the Opteron fully supports 32-bit applications, but requires that programs be optimized and recompiled to take full advantage of the 64 bits. The 64-bit version of Windows XP also takes advantage of the increased CPU word size. Intended for servers and high-end workstations, the Opteron competes with Intel's Xeon and Itanium lines. AMD subsequently introduced 64-bit Athlon CPUs (see Athlon).

Multicore Opterons
In 2005, following the introduction of its Athlon dual-core chips, AMD introduced dual-core Opterons with quad-core compatibility (dual cores could be replaced with quad-core chips on the same motherboard). In 2007, it introduced the Quad-Core AMD Opteron processor (code named Barcelona). See Hammer, Xeon and Itanium.