Guide to Reducing Power Consumption of an Inexpensive Media Server by Undervolting

Conan Mercer Applied Scientist

Guide to Reducing Power Consumption of an Inexpensive Media Server by Undervolting

16 Apr 2021 - Conan Mercer

Power Hunger

In a previous post I built an inexpensive media server from reused computer parts, blog post here. It was a successful build for the most part, costing little money and offering a big improvement to my home entertainment setup. There was one nagging issue though, power consumption was high.

The main reason for this high power consumption was the CPU used in the build. The AMD FX-8320 is, and always was, a power hungry CPU. Not wanting to buy any new parts for this server, after some thought I came up with the plan of providing less power to the CPU in order to reduce its power consumption. For this I undervolted the CPU in the BIOS. The settings can be seen in the table below.

Undervolting the AMD FX-8320

Setting State
AMD Turbo Core Technology Disabled
CPU Voltage 1.130500 V
CPU-NB Voltage 1.180667 V
BIOS setting for a successful undervolting of the AMD FX-8320

Any voltage combination lower than the above resulted in the system becoming unstable and crashing. This is as low as I could go.

Power Consumption Results

Using my local rate of electricity of 0.170105 €/kWh, and assuming a usage of 3 hours per day at idle and 21 hours a day in sleep mode, the electrical cost of the server is as follows.

Before, the server was idling at around 120 watts, which was costing about 29€ per year. Now the server idles at around 80 watts, costing about 21€ per year.

Bar plot of the server watt consumption before and after undervolting

The average power consumption of the server has dropped by 40%. Not bad considering we did nothing but change some settings in the BIOS. This technique will work on similar hardware, so if you have a configuration that is using less initial wattage than mine, it may be possible to still reduce down the power consumption by undervolting.

Conclusion

The media server is now more power efficient, although admittedly newer hardware or even some old hardware could do the same job with less power.

In the future I will look into buying older hardware that is more power efficient, mainly a CPU change (and perhaps a motherboard if the current architecture wont support the new CPU).

I may also look at a Raspberry Pi based system to get the energy costs down. Although if I expand this server to do much more, the Pi may not have enough horses under the bonnet to supply what I would need.