The server components get their power through a Power Supply Unit (PSU). PSUs convert AC electricity from a data center’s mains power supply to DC electricity for the server hardware (Ibraheem, 2020). They are generally very efficient, but some losses are unavoidable. To estimate this power supply loss figure, Tailpipe examined the following series of sources.
First, Tailpipe looked at the available market data on PSU efficiency. The 80 PLUS certification is the market standard for PSUs, guaranteeing that a certified PSU delivers a minimum of 80% efficiency across various load levels and with different voltages of AC power. Most major manufacturers, such as HPE, guarantee that all their PSUs are 80 PLUS certified. 80 PLUS delivers six tiers of certification, across a scale of 80-94% minimum efficiency. This means we can confidently estimate that the PSU efficiency of cloud servers is, at minimum 80%.
Tailpipe then looked at the available published research on PSU efficiency. Texas Instruments claims that most of the PSUs on the market developed and released since 2022 target the top tier 80 PLUS Titanium certification, with a 90%-96% minimum efficiency across different load levels. This is supported by Corsair, which claims that most PSUs operate at between 80-96% efficiency. Additionally, in the case of AWS, VP James Harrison made a public statement as far back as 2016 that AWS server power supply units run at a minimum 90% efficiency.
PSUs have developed since 2016, and it is in the interests of Cloud Service Providers to utilize PSUs that are extremely energy efficient, so Tailpipe assumes an average PSU efficiency of 96%. This means that a 4% power supply loss is integrated into the methodology by multiplying the total power consumption of the components by 1.04.
This same 1.04 figure is used as the Power Supply Efficiency Factor in the calculation for Network Storage.
