In early 2002 it became known that the AMD had working samples of the sucessor of the Athlon XP, the new ClawHammer CPU's. It wasn't until late 2002 for early benchmarks to leak out. ClawHammer made it's debut at 22 April 2003 in the form of an Opteron. At 23 September 2003 the Athlon 64 was launched. Read the story of the Athlon HX 1400 which is a early Athlon 64 from May 2002.

ClawHammer is manufactured at 130nm, the same process technology as the last iteration of Athlon XP. It features an on-die memory controller that operates at the same clock speed as the CPU and has a shorter path to the memory. This shorter path results in lower latency, enhancing system performance. Several improvements have been made to enhance branch prediction reduce latencies and optimise SSE instructions.

ClawHammer also incorporates Cool ’n Quiet; a technique similar to Intel SpeedStep that reduces the clock frequency when the CPU is idle. This technique is now standard in modern CPUs but was new in 2002/2003. AMD also utilised a heatspreader to protect the vulnerable processor core.

The processor is equipped with a HyperTransport bus as its front-side bus. This bus is faster and effectively supports 2-way and 4-way multiprocessor systems. Four-way systems were only available for SledgeHammer cores, which are essentially identical to ClawHammer but with a 1MB L2 cache instead of 512KB.

Finally, ClawHammer is AMD’s first 64-bit processor. It is not a new architecture (unlike Intel IA-64 for Itanium systems) but an evolution of the x86 architecture. The term x86-64 was previously used but later AMD64 became the standard designation. Intel also implemented x86-64 instructions known as Intel EM64T (often mispronounced as EMT64) which it later renamed to Intel 64.