Several dual-core versions of the Opteron processor were released, all using the socket 940 platform. We'll talk about them all, but first let's take a look on the dual-core Opteron architecture on Figure 4.

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Figure 4: Dual core Opteron architecture.

There are two main difference between Opteron and Athlon 64 processors. First is the memory support. Both have dual channel support, but Opteron requires registered memories, which are targeted to servers. The second main difference is the number of HyperTransport busses the processor has. Athlon 64 has just one HyperTransport bus, while Opteron can have one, two or three busses. Actually Opteron is manufactured with all three HyperTransport busses, but one or two are factory disabled depending on the processor model.

The Opteron 1xx series doesn't support multi processing and has only one HyperTransport bus. The Opteron 2xx series support multi processing up to two CPUs and has two HyperTransport busses. And the Opteron 8xx series support multi processing up to eight CPUs and has three HyperTransport busses. These extra busses are used to link one CPU to another.

Dual-core solutions were released on the 2xx and 8xx series. As you can see from the table below, dual core models numbering system advance in increments of five versus increments of two on the single core Opterons. The released models are the following.

Model	Frequency	Price *
875	2.2 GHz	USD 2,649
870	2.0 GHz	USD 2,149
865	1.8 GHz	USD 1,514
275	2.2 GHz	USD 1,299
270	2.0 GHz	USD 1,051
265	1.8 GHz	USD 851

* Prices for distributors in the USA in 1,000 quantities.

We can speculate that AMD will also realease dual core models on their Opteron 1xx series.

Performance

AMD says that their new Opteron 275 (2.2 GHz) is 87% faster than Opteron 248 (2.2 GHz) and 69% faster than Opteron 252 (2.6 GHz) on SPECjbb2000 benchmark.

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Figure 5: Dual core Opteron performance, according to AMD.