AMD has traditionally used its workstation/server range of Opteron processors to début new technology. Opterons were the first dual-core and quad-core AMD CPUs, and are now also the first AMD CPUs with six physical cores. These new six-core Opterons are known as the 2400-series and 8400-series - the only difference being that up to two 2400-series Opterons can be installed in a motherboard, while up to eight 8400-series Opterons can be used.
Both types of new Opteron use the same Socket F packaging as that of their predecessors, but as we doubt that many bit-tech readers build servers for a data centre, we decided to take a look at the Opteron 2435, the highest-spec 2400-series model.
The Opteron 2435's six cores are clocked at 2.6GHz, which is higher than any other six-core Opteron but 500MHz slower than the fastest quad-core Opteron, the elusive 2393SE. We say elusive, because despite our best efforts we've been unable to find a single Opteron 2393SE in the UK, let alone a pair. As a result, we had to test the Opteron 2435 against the next best available Opteron, the 2382, which is clocked at 2.6GHz.
Despite having two more cores than earlier Opterons, the new 2435 has the same low TDP of 75W - nearly half the 130W of Intel's fastest workstation/server CPU, the Xeon W5580.
AMD hasn't just added another two cores to the Opteron 2435 though; there are also several new architectural features. The most important of these is the upgraded Hyper-Transport link, from version 1.0 to version 3.0, thus increasing its effective frequency from 1GHz to 2.4GHz.
As the Hyper-Transport bus is used for all communications between the CPU and the rest of the system, this should yield a substantial performance increase in all applications. Unfortunately, as no dual-processor Socket F motherboards support Hyper-Transport 3.0, the Opteron 2435 is forced to run at 1GHz. Hyper-Transport 3.0-compatible motherboards based on a new AMD chipset are due for release in a couple of months.
The Opteron 2435 also marks the introduction of another new feature - HT Assist. This technology helps to cut down the number of probes a core must perform when searching for data that may be stored in another core's cache. Although this is unlikely to significantly improve performance in a dual-processor, 12-core system, it should provide more of a boost in a four or eight-CPU configuration with 24 or more cores.