xAI's Colossus Runs All Night. So Do the Turbines.

xAI's Colossus Runs All Night. So Do the Turbines.

A high-pitched whine, a constant engine drone, a low-frequency rumble that never stops. That is what residents of Southaven, Mississippi, have been hearing day and night since the summer of 2025. The source is the bank of gas turbines powering Colossus, the supercomputer built by xAI, Elon Musk's AI company.

On June 8, 2026, three residents filed suit in Mississippi federal court on behalf of an estimated class of more than 10,000 people. They describe noise that is "invasive and inescapable," shredded sleep, ringing ears, and home values in freefall. The complaint targets xAI, SpaceX, and a subsidiary called MZX Tech, and asks for damages plus an injunction to bring the noise down. xAI says it has tried to muffle the sound. The plaintiffs say they can't hear the difference.

A Perfect PUE Says Nothing About What Happens Outside the Fence

This piece is the second half of a diptych. In the first part, we showed that the green metrics data centers love to quote, PUE for energy and WUE for water, are either unverifiable or quietly accounted away. Here is the direct sequel to the loose end we left hanging: even when it's calculated honestly, a perfect PUE tells you nothing about where the electricity came from or about the people living 500 meters away.

PUE measures exactly one thing. The ratio between a data center's total electricity and what actually reaches the servers. A good score means little power is lost to cooling or technical overhead. It says nothing about how that power was generated. Coal, nuclear, or gas turbines parked in a residential neighborhood: to PUE, it's all the same.

That's the metric's structural blind spot. It rates the efficiency of the installation, not its footprint on the world around it. Noise, air quality, the neighbors' sleep, none of it enters the calculation. The boundary stops at the data center fence. Everything that spills past, the gas burned to make the power, the fumes, the racket, is by definition out of frame.

The Cost Is Real. It's Just Outside the Frame.

The numbers in the xAI case give a sense of what the metric never sees. To run Colossus, the company installed dozens of gas turbines. By most counts, which climbed month after month, the site went from a handful of units to more than fifty in under a year. The air permit issued by Shelby County allowed only 15, rated at 247 megawatts. Environmental groups counted far more, up to 35 running without authorization before the operation was regularized.

Those turbines can emit more than 1,700 tons of nitrogen oxides a year, smog precursors. Enough to make them the single largest industrial source of that pollutant in greater Memphis, according to the Southern Environmental Law Center. That's a second legal front: in April 2026, the Mississippi NAACP sued xAI for violating the Clean Air Act. The downwind neighborhoods, Boxtown and Whitehaven, are majority Black. Whitehaven posts an asthma hospitalization rate 2.8 times the state average, per the county health department.

All of that cost is real, measurable, documented across a complaint dozens of pages long. None of it shows up in a single energy efficiency report.

The State Line as a Sleight of Hand

The geographic detail is almost too on the nose. The Colossus data centers sit in South Memphis, Tennessee. The gas plant that powers them is on the other side of the border, in Southaven, Mississippi. Efficiency is tallied on one side of the line; the gas burns and the noise screams on the other.

It's the picture of what the metric does at smaller scale. It draws a frame around the installation, computes a clean ratio inside it, and leaves everything else out of view. The neighbor who can't sleep is not a variable in the PUE. He's in another county, another state, another accounting perimeter.

The efficiency the AI giants advertise isn't a lie. It's just incomplete by construction. A perfect ratio doesn't erase the cost of compute. It relocates it somewhere nobody is counting, within earshot of people who never signed up to live next to a power plant.