Power consumption

Website: Prime95

Performance per watt is fast becoming an important metric for deciding which hardware to buy, especially if you have multiple PCs. To determine the power efficiency of various CPUs, we measured the power draw at the wall of each test system while running the small FFT test of Prime95 on every available process thread.

In this configuration, the Opteron 2435s drew 310W, a small drop down from the 327W consumed by the Opteron 2382s. This is all the more impressive when you consider that the Opteron 2435 system has four more cores and higher-frequency RAM. In contrast, the Xeon W5580s drew an energy-guzzling 386W from the wall. While this is hefty increase in power consumption, the far greater performance of the Xeon W5580s means that they're more power efficient, as you'll be able to complete tasks quicker with a Xeon system

Final Thoughts

Clearly, AMD has done a great job engineering the Opteron 2435, as these six-core CPUs have a very similar thermal profile and power consumption to that of a pair of identical frequency quad-core Opterons. Given the extra performance, the six-core models provide in certain applications, this is no mean feat.

However, while the comparatively low power draw of the Opteron 2435s may make them attractive to those upgrading a power-starved data centre, the way by which AMD has artificially limited performance by keeping the clock frequency down means they aren't an attractive purchase for a workstation or HPC server.

In these scenarios, the most important aspect is how much processing power you can squeeze into a single box, and for that, the Xeon W5580 reigns supreme, especially now that their price has tumbled by nearly £300 to £1,198.57 inc VAT.

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