AMD A8 3870K review

Power Consumption

Power consumption wise, AMD was able to keep the TDP of these APUs on track, either 60W or 100W depending on your choice of APU. A higher power draw would result in unhappy customers, but obviously also could endanger heat levels.

Temperatures with our test setup and that old OCZ Vendetta heatpipe based cooler remained at roughly 50 Degrees C under full load. So that should just not be an issue.

The Llano APU is a pretty clever product when it comes to its power design and power states. Not only can the processor cores independently be throttled down, lowering voltage and what not, there are different power states inside the APU allowing nearly complete shutdown of segments/domains within the APU. For example, if the GPU is not used, it can be powered down. The same goes for CPU cores.

Above, that very cool FLIR image shows temperature differences (leakage) with several power states applied (gates opened up and closed), you'll see the APU all lit up with all domains enabled, but when not in use the UVD core logic can shut down, or sure -- even the graphics core. That makes the APU very flexible in terms of power gating versus power consumption and helps out in that everlasting denominator, heat.

We ran the AMD A8 3870K APU both with and without a dedicated graphics card. Without one (using the internal IGP) the PC idles at only 39 Watts, very respectable. When we place load on the CPU and we see the power draw rise the system now consumes roughly 110~120 Watts. This is with merely an SSD and 8GB memory installed. Your average PC will draw a little more power if you add optical drives, HDDs, soundcards etc.

When we put a dedicated graphics card (above chart) into the PC (GeForce GTX 580) our IDLE power consumption immediately increases towards 102 Watts. And once we stress the CPU cores of the APU we get a 176 Watt power draw.

I want to make it very clear that power consumption measurements will differ per PC and setup. Your attached components use power but your motherboard can also have additional ICs installed like audio controller, LUCID chips, network controllers, extra SATA controllers, extra USB controllers, and so on. These parts all consume power.

Under stress with a cheap heatpipe cooler you are looking at 40 to 50 Degrees C on the APU. No problem.

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