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Equation 5 · Part 2 · AI Datacenter Power and Cooling: A First-Principles Introduction

Symbol E_IT

PUE=EfacilityEIT.\mathrm{PUE} = \frac{E_{\mathrm{facility}}}{E_{\mathrm{IT}}}.
EITE_{\mathrm{IT}}

What this part means

EIE_IT occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

Its job in the formula

EIE_IT occurs below the fraction bar. The quantity above the bar is divided by this expression; zero is excluded as a denominator.

The passage around this formula

Two ratios recur throughout this series, and both are simpler than their reputation suggests. Power usage effectiveness compares the total electricity a facility draws to the electricity that reaches the computing equipment itself: PUE=EfacilityEIT\mathrm{PUE} = \frac{E_{\mathrm{facility}}}{E_{\mathrm{IT}}}. The Green Grid, the industry consortium that introduced the metric in 2007 and later consolidated its guidance into a single reference document, defines it plainly: “PUE for a dedicated building is the total facility energy divided by the IT equipment energy. PUE is an end-user metric used to help improve energy efficiency in data center operations” [ 5 ] . An ideal value is 1.0, meaning every watt drawn by the site reaches the computing load;…

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A subscript is a label attached below a symbol. It often selects a time step, component, category, or member of a sequence.

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