One, Two, Four... Or How About Eight CPUs?

Overview of model numbers and HT channels

The way the Opteron processors are named is only confusing at first glance. If you look closely you will detect an easily comprehensible system, which first and foremost determines the number of HyperTransport channels. We will deliberately dispense with the "HT" abbreviation here, to prevent any confusion with Intel's HyperThreading.

Every HyperTransport channel is designed to be bi-directional and works with 16 bits. A 200 MHz speed (quad-pumped, the clock speed adds up to 800 MHz) yields a bandwidth of 3.2 GB/s - or 1.6 GB/s per direction. The channels are used to respond to either an I/O device (e.g. PCI-X bridge, AGP) or another Opteron processor. Each Opteron basically has a dual-channel memory controller.

A system with two Opteron processors.

A 4-way system.

This is what an eight- or multi-processor system looks like. However, this is intended exclusively for the server world.