Data center · Methods
The physics, and how far to trust each number
The animation on the overview page is drawn from two equations and a handful of published figures. This page shows the working so you can check it, then explains how sources are graded.
Every watt in is a watt of heat out
A processor does no mechanical work and stores no energy. Apart from a negligible amount leaving as network signals, all the electrical power a rack draws ends up as heat in the room or in the coolant. That is why a 132 kW rack needs 132 kW of heat removal, continuously.
The heat a moving fluid carries away is its mass flow, times its specific heat, times how much it warms up:
Two worked checks against published specs
Air: NVIDIA DGX B200
NVIDIA publishes 14.3 kW maximum draw and 1,550 CFM of airflow.
× 1.2 kg/m³ = 0.878 kg/s of air
ΔT = 14,300 ÷ (0.878 × 1,005) = 16.2 °C
Air entering at 25 °C leaves at about 41 °C. As a cross-check, 14.3 kW × 3,412 = 48,792 BTU/hr, and NVIDIA's guide lists 48,794.
Liquid: NVIDIA GB200 NVL72
HPE puts 115 kW of the rack's 132 kW into liquid. A server maker (QCT) gives up to 130 L/min and a 45 °C inlet for this rack.
× 0.990 kg/L = 2.145 kg/s of water
ΔT = 115,000 ÷ (2.145 × 4,180) = 12.8 °C
Coolant entering at 45 °C returns near 57.8 °C, inside the 65 °C maximum return the same document states. That is eight times the heat of the air example, carried in a flow about 340 times smaller by volume.
Constants used
Water near 45 °C: density 990 kg/m³, specific heat 4,180 J/(kg·K). Air near 20 °C at sea level: 1.2 kg/m³ and 1,005 J/(kg·K).
Where it is approximate
Real loops usually run a water and glycol mix, which holds less heat per liter, so the true rise is somewhat higher. Air density falls with altitude and temperature, so a high site needs more airflow.
What is assumed, not published
The Vera Rubin flow rate is calculated by assuming the same 12.8 °C rise. The air stream's warming in the GB200 view is drawn at an assumed 12 °C. Both are labeled where they appear.
The homes comparison
The average US household used 10,791 kWh in 2022, an average draw of 1.23 kW. A 132 kW rack equals about 107 of them; a 240 kW rack about 195.
How sources are graded
| Mark | Means | How to treat it |
|---|---|---|
| No tag | The chip vendor's own product page, datasheet or user guide. | Reliable for planning. Still confirm at quote time. |
| maker | A server maker's datasheet or spec sheet. | Reliable for that maker's system; other makers' builds differ. |
| calc. | Calculated here from published figures, such as power supply capacity. | An upper bound or a derived value, not a measurement. |
| est. | Press, analysts, resellers or marketplaces. | A lead to verify. All prices fall here. |
On October 7, 2026 every figure in these tools was re-checked against its cited source in a separate pass, and the estimator's arithmetic was recomputed independently. That review corrected several prices, source attributions and labels; figures no source supported were removed or marked. Before that, key figures for eight products were checked directly against the vendor or server-maker page and matched: maximum draw for DGX H200, B200 and B300; GB200 rack power and layout; GB300 nominal, peak and provisioning power; Vera Rubin memory and inlet temperature; MI355X memory and power; and Arc Pro B70 memory and power. Source pages were read through an automated fetch tool that summarizes them, so a figure can still be misread; follow the link before relying on any single number.
Where a number could not be traced to a credible source, the field says so. Nothing is filled in from memory.
Scope
Included
Data center accelerators from NVIDIA, AMD and Intel that can be bought for on-premises deployment in the United States, plus announced products expected within about six months.
"Fits" is by power only
The fit guide divides the rack budget by one system's power. It ignores rack space, floor loading, networking and redundancy.
Left out, and why
All sources
Vendor documents
Server-maker documents
Press, analysts and resellers
Figures come from public vendor, server-maker and press sources, last checked on October 7, 2026.