In our previous Trinity test session we didn’t reveal any improvements in the energy-efficiency of the new Socket FM2 platform compared with Socket FM1. However, AMD claims that it is not true. It could be the fact that last time we only tested the system power consumption when the load fell on the graphics core. Let’s see what will happen once we install a discrete graphics card into our test system and all the work will be in the hands of x86 Trinity cores.
To get a better idea of how greatly the processor’ energy-efficiency actually improved we performed a round of special tests. The new digital power supply unit from Corsair – AX1200i – allows monitoring consumed and produced electrical power, which we use actively during our power consumption tests. The graphs below (unless specified otherwise) show the full power draw of the computer (without the monitor) measured after the power supply. It is the total 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 version of LinX 0.6.4-AVX utility. Moreover, we enabled Turbo mode and all power-saving technologies to correctly measure computer's power draw in idle mode: C1E, C6, Enhanced Intel SpeedStep and AMD Cool’n’Quiet.
In idle mode any contemporary processors will switch to special power-saving states, in which their power consumption will be very low – only a few watts. In this case the power appetites of other system components and the efficiency of the voltage regulator circuitry on the mainboard start to matter more. Therefore, AMD A10-5800K is at the top of the diagram. Asus F2A85-V Pro mainboard we used for our tests has one of the most efficient voltage regulators under low operational loads. However, this circuitry design is partially inspired by the peculiarities of the processors themselves. Trinity features fine-grain power gating, which powers off a lot of knots inside the processor in idle mode.
You can clearly see how it works during single-threaded load:
Trinity consumes more power than Llano. However, in fact, it should be compared against the quad-core Bulldozer processor with the similar microarchitecture. This is where it becomes clear that the energy-efficiency improvements are definitely there.
No doubt that it is Core i3 3000-series processors that allow building the most energy-efficient systems. However, among all today’s testing participants from AMD, A10-5800K demonstrates the best peak power consumption readings under heavy computing load. This progress strikes as particularly impressive taking into account that they didn’t switch to finer manufacturing process.