Whenever we talked about energy-efficiency our previous tests showed multiple times that Intel processors were beyond competition. However, we haven’t yet tested the low-end solutions. To make up for this omission we performed a special test session. The numbers below show the total power consumption of the complete tested platforms (without the monitor). During our tests we used 64-bit LinX 0.6.3 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.
All testing participants consume almost the same amount of power in idle mode, AMD based solutions being a little more efficient.
However, things change dramatically when the computational processor load increases. Celeron as well as Pentium processors turn out more energy efficient than AMD CPUs with identical performance. And this difference is quite significant and makes almost 20 W. I have to say that this serious power consumption difference is determined particularly by the CPU electrical characteristics, as we see from the power consumption of a CPU alone measured without the rest of the platform.
The numbers on the diagram show the power consumption along the 12 V power line connected directly to the processor voltage regulator on the mainboard. Although this approach didn’t take into account the efficiency of the processor voltage regulator, we have every reason to state that there is a gigantic gap between AMD and Intel CPUs in performance per watt. And this gap is obviously not in AMD’s favor, even taking into account that the memory controller in Athlon II and Sempron based systems is located inside the processor, while on LGA775 platforms it is in the chipset North Bridge. So, lower power consumption of Socket AM2+/AM3 mainboards can’t make up for the low energy efficiency of CPUs on K10 (Stars) microarchitecture.
Although I can’t help pointing out the fact that LGA775 mainboards for Intel processors with integrated graphics consume about 10 W more power than mainboards for AMD CPUs.