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Power Consumption

Junior Bulldozer modifications do not impress us in the performance tests. However, unlike their eight-core brothers, they belong to a class of products with 95 W thermal envelope, which allows us to hope for their relative energy-efficiency. Let’s see what the practical power consumption tests will show.

The graphs below show the full power draw of the computer (without the monitor) measured after the power supply. It is the total of the power consumption of all the system components. The PSU's efficiency is not taken into account. The CPUs are loaded by running the 64-bit LinX 0.6.4 utility. We enabled all the power-saving technologies for correct measurement of the computer's power draw in idle mode: C1E, AMD Cool'n'Quiet and Enhanced Intel SpeedStep.

In idle mode when all processor power-saving technologies kick in platforms based on AMD FX processors look quite good in terms of their power appetites. The CPUs obviously contribute very little to the overall system power consumption in this case and the 40 W reading for the most part comes from all other system components. Therefore, the results for AMD FX, AMD Phenom II X4 and Sandy Bridge products are very similar.

It is interesting to test the systems power consumption under single-threaded load because in this case all contemporary processors enable their Turbo mode, which boosts the performance while keeping power consumption and heat dissipation within acceptable range. Nevertheless, processor makers have different understanding of the term “acceptable range”, so different Sandy Bridge modifications prove much more energy-efficient. At the same time, the actual power consumption of AMD FX processors under single-threaded load is lower than that of their predecessors. Although as our tests showed, their performance in this case is also lower.

When all processor cores are fully loaded with multiple computational threads, the power consumption of eight-core 125 W AMD FX CPUs reaches that of six-core Phenom II X6 with the same declared TDP. However the actual power consumption of the junior Bulldozer modifications, FX-6100 and FX-4100, with lower declared TDP is quite naturally about 30-35 W lower. Although, this is still not enough to make the platform built on the junior Bulldozer models as energy-efficient as the competing configurations built around Intel CPUs.

 
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