Rationale

A few days ago I was building rack 19″ server based on AMD Athlon 5350 CPU. The main goal was to create a hardware set that will operate on wide supply voltage ranges (48V, 24V, 19V) and will be power efficient.

I decided to take a look at quite cheap AMD AM1 Athlon APU with TDP said to be 25W.

Testing platform

The hardware:

• AMD Athlon 5350 CPU (4 cores, 2.05Ghz, 2MB L2 Cache)
• MSI AM1I Motherboard
• Crucial Ballistix 8GB (2x4GB) DDR3 1600MHz
• Kingston SSDNow! V300 120GB
• PicoBox Z3-ATX-200 Power supply unit.
• Gembird rack 19″ 2U chasis with 2 fans connected to 12V

Some facts about software:

• Gentoo linux with kernel 4.0.5
• Semi-tickless kernel with 300MHz ticks
• Conservative CPU Speed governor with 800MHz to 2.05Ghz frequency

Testing hardware:

• Standard DC power supply with voltage and current monitoring, set to 24.1V

The „idle” state: Operating system running, one ssh client connected, no tasks

The „full load”: Linux kernel make -j5

In idle state, CPU Speed governor set minimal frequency on all cores. For testing purposes I also forced maximal frequency to check for differences.

In full load state CPU Speed governor set maximal frequency of course, I also forced minimal for checking.

The results

The table below show total power consumption under different conditions.