AMD’s socket 939, 64-bit Athlon 64 X2 dual-core is the heart of the system. It provides slightly better performance than most single-core, dual-processor motherboards because of the tight integration and it provides significantly better performance than a hyperthreading architecture. The architecture supports 32- and 64-bit applications. A 64-bit operating system is necessary to take advantage of the 64-bit architecture, although a 32-bit operating system like Windows XP Pro will take advantage of both cores.
A crossbar switch links the two processors with the 16-bit, 8-Gbit/s HyperTransport and integrated 128-bit, dual-channel memory controllers with ECC support. Each core has its own 256-kbyte L1 and 2-Mbyte L2 cache. A 48-bit virtual address scheme maps to a 40-bit physical memory address. The chip incorporates the enhanced virus protection feature found in Windows XP with service pack 2.
As with most 64-bit processors, the Athlon 64 X2 gets a bit warm, but less so than the competition. Power dissipation ranges from 89 W to 110 W. The top-of-the-line model 4800+ runs at 2.4 GHz. Slower versions are available that also have smaller caches.