@Hattig
Regarding AMD's K8 processor family from AMD's official web site.
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Q: Will all AMD Opteron processors support HyperTransport technology? How many links?
A: The AMD Opteron processor architecture is designed to support up to three HyperTransport links, which can provide up to 19.2GB/sec peak bandwidth.
Q: What are the differences between the AMD Opteron processor and the AMD Athlon 64 processor?
A: The primary difference between the AMD Opteron processor and the AMD Athlon 64 processor is in the number of HyperTransport links embedded on the chip. The AMD Athlon 64 processor contains one HyperTransport link offering 6.4 GB/s data transfer while the AMD Opteron processor offers three links. The processors also contain different amounts of cache.
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Reference:
http://www.amd.com/us-en/Processors/ProductInformation/0,,30_118_4699_7981%5E7987,00.html#19839