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Power Consumption

We decided to start our practical experiments with the new AMD processor with the most interesting aspect power consumption and heat dissipation. Increased clock frequency results into pretty predictable increase in performance, but the changes in the electrical and thermal parameters are a totally different question, especially since AMD did raise the TDP by 15 W for the new Phenom II X4 965 processor compared with the predecessors.

The numbers below show the total power consumption of the tested platforms (without the monitor). During our tests we used 64-bit LinX 0.5.8 utility to load the systems to the utmost extent. Moreover, to ensure that we estimate the power consumption in idle mode correctly we activated all power-saving technologies, such as C1E, Cool'n'Quiet 3.0 and Enhanced Intel SpeedStep.

In idle mode when the tested platforms didn’t bear any processor load, things do not look too bad. Phenom II X4 965 power consumption is about the same as the power consumption of the previous Phenom II X4 955 model. Moreover, the AMD Dragon platform show overall better results than the LGA1366, which consumes much more power in idle mode because of higher mainboard and triple-channel memory power needs. But the best result belongs to the old Intel platform with an LGA775 Core 2 Quad processor.

When CPU utilization increases to 100% the general results ratio remains the same. Core i7-920 platform demonstrates the highest power consumption readings. Even though AMD platform started to consume much more power with the new Phenom II X4 965 processor than it used to with Phenom II X4 955, it is still “behind” the LGA1366 system. However, if you are really interested in power system consumption parameter, then you should forget about mainstream AMD processors: even the regular, not energy-efficient CPUs as Core 2 Quad, offer much better performance per watt ratio. Besides, Intel also offers energy-efficient quad-core solutions from the S-series that boast additionally lowered power consumption and heat dissipation.

To get a better idea of the situation, we performed a separate Phenom II X4 965 power consumption test under heavy load when none of the other system components are taken into account. To be more exact, we measured the consumption along the 12 V power line connected directly to the processor voltage regulator on the mainboard. In other words, this measurement method didn’t take into account the efficiency of the voltage regulator circuitry.

This is where we understand that relatively acceptable readings taken off the AMD Dragon platform are determined mostly by the energy-efficiency of the mainboard chipset. When we measured the actual Phenom II X4 965 CPU power consumption, we got a frightening number that is just a little below 150 W. And it is not just twice as much as a Core 2 Quad processor with comparable performance will consume, but is way higher than the actual power consumption of the Core i7 with 8 virtual cores and not 4. In other words, Phenom II X4 965 has very frustrating power consumption. Even though it is manufactured with 45 nm process, its electrical needs are comparable with those of the top models from the first Phenom generation manufactured with 65 nm technological process.

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