| The Opteron 1xx chips are single processor only. The Opteron 2xx chips are designed for two way operation. The Opteron 8xx chips are designed to operate up to eight way. There are motherboards that support one way, two way and four way currently. Otherwise, there's no real difference between the various Opteron chips, apart from cost!
If you want a four way system, the Tyan K8QS Pro supports four way, and each processor has it's own bank of RAM. Some multiway boards do not allocate RAM to each processor. This can slow down the processors, as they do not have any local RAM, and have to spend time fetching across the hypertransport links.
There are a number of two way Opteron boards out there, but I couldn't personally recommend any of them, as I've not used any!
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