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Equation 2 · Part 7 · How Grok and Colossus Actually Work, as Far as the Record Shows

subscript

PˉGPU,2=PtotalN2=2,000 MW555,000≈3.6 kW per GPU,\bar{P}_{\text{GPU},2} = \frac{P_{\text{total}}}{N_2} = \frac{2{,}000\ \text{MW}}{555{,}000} \approx 3.6\ \text{kW per GPU},
subscript

What this part means

The lower label selects a particular version, component, or indexed member of the quantity. For example, x₀ and xₜ can be values at different positions.

Its job in the formula

A subscript distinguishes a version, component, step, or member of a quantity. It does not automatically mean multiplication.

The passage around this formula

Colossus 2 is the clearest example of a figure that belongs squarely in the vendor-claim column rather than the confirmed-fact one. On December 30, 2025, Elon Musk announced that xAI had purchased a third building in Memphis, expanding the campus toward a stated 2-gigawatt total capacity and roughly 555,000 GPUs, reported to represent about $18 billion in accelerator purchases — implying, by simple division, something on the order of $32,000 per GPU [ 10 ] . The reporting is explicit that this is Musk’s own announcement rather than an independently audited figure, and the newer accelerator generation involved (GB200- and GB300-class parts, alongside roughly 30,000 legacy H100/H200 units…

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Learn the underlying idea

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

Open the illustrated subscripts: which member of a family? guide →

Sources cited in the surrounding passage

These citations provide research context; check each source for the exact claim it supports.