The Bill for Not Falling Behind: The Capital Half-Life of AI Hardware

Prefer reading in Arabic? Read the Arabic version on Substack Every quarter, the big technology companies tell us how much they spent. They don't tell us how much of that money bought back capacity they already had. The filings we reviewed don't separate the two. In 2025, Amazon changed its mind about how long some of its servers would last. It had raised the estimated useful life from five years to six. Then it moved a subset back down to five. The reason it gave in its own filing was blunt: technology was moving faster, "particularly in the area of artificial intelligence and machine learning." Shortly before that, the company had booked roughly $920 million in accelerated depreciation and charges tied to retiring equipment early. (SEC) At a small company, an accountant would note this and move on. At a company building one of the largest compute fleets on the planet, a single year on the life of a server moves serious money. And the striking part is that this decision did not come from a company losing customers. In the second quarter of 2026, AWS reported $42.2 billion in revenue and $16.6 billion in operating income, and Amazon said its AI business inside AWS had passed a $25 billion annualized revenue run-rate. (SEC) So the demand is there, and the revenue is real. And yet the company's trailing-twelve-month free cash flow fell to negative $7.6 billion. The reason Amazon itself gave: a $66.1 billion increase in purchases of property and equipment, which "primarily reflects investments in artificial intelligence infrastructure." (SEC) Both of the ready-made stories collapse here - the bubble and the gold mine. AI can generate money and consume capital in the same breath. Which opens a sharper question. When a company writes the next hundred-billion-dollar check, how much of it adds new computing capacity to the world, and how much of it buys back capacity that is starting to slip? Obsolescence Reaches the Books Before Amazon's reversal, the traffic was all going the other way. Microsoft extended the estimated useful life of its server and network equipment from four years to six, effective with its fiscal 2023, which raised operating income by $3.7 billion and net income by $3.0 billion. (SEC) In January 2023, Alphabet raised the life of its servers from four years to six and certain network equipment from five to six, cutting depreciation expense by $3.9 billion and lifting net income by $3.0 billion. (SEC) And in 2025, Meta extended most of its servers to five and a half years, reducing depreciation by about $2.9 billion. (SEC)1 These extensions may well reflect better hardware management and a genuine ability to keep machines useful for longer. But they also tell you something about the nature of the number. An accounting life is a management estimate, and one extra year does not just change the page - it changes the profit printed on it. Which is what made Amazon's reversal worth noticing. In the same filing, the company estimated the decision would reduce its 2025 operating income by about $0.7 billion, with accelerated depreciation taking another $0.6 billion. (SEC) When a company shortens the life of its own assets knowing exactly what that will cost it, it isn't flattering anyone. The pace of technical change had moved out of conference panels and into a line item. Ninety-One Billion, Undivided For three decades, software was the light industry: lines written once and sold millions of times, at high margins and enormous scale, with no factory and no smokestack. Then the rule flipped. Microsoft gives us the clearest window onto the fast-moving part of the new spending. In four years, its cash outlay for property and equipment jumped from about $23.9 billion to $115.9 billion. (SEC) The same trajectory shows up at Alphabet, Meta and Amazon, though fiscal years and spending definitions differ.2 As for the number the headlines like - roughly $700 billion when you add up the big companies' guidance - that describes plans that can still be revised, not money paid. Add up what Microsoft's management called capital expenditure across its fiscal 2026 quarters and you reach about $145.3 billion. From the company's own description of the mix, roughly $91.1 billion of it - about 63% - went into short-lived assets, led by processors, GPUs and network gear.3 Ninety-one billion dollars in twelve months, from one company, on equipment whose clock runs faster than the building's. Timing complicates the arithmetic further. At the end of 2025, Alphabet held about $78.6 billion in assets not yet in service. By June 2026 that figure was $122.8 billion - around 40% of its $304.3 billion in total gross property and equipment, of which technical infrastructure accounts for $247.2 billion. (SEC) A single asset has three separate moments: the day it is paid for, the day it starts working, and the day the next generation starts pressing on its value. Months can separate them. So you cannot take one year of spending, add five years, and announce the date the replacement bill comes due. And here stands the question no published document answers: how much of those billions expanded the fleet, and how much replaced what was already there? That is the missing number. The rest of this essay examines the forces that make it bigger or smaller, until we reach what the figures actually support - which is more than it first appears. The Old Chip Doesn't Die The strongest argument against the idea of permanent replacement is simple: a chip doesn't end the day its successor arrives. It moves down a rung. A processor that has dropped out of frontier training moves to running models after training - inference - or serves smaller models and customers who care more about price than about the latest performance. The market shows this second life is real. In September 2026, the hourly price of an A100 with 80GB ran from about $0.45 at the bottom of the surplus-capacity marketplaces - where individuals and small operators sell unused cycles at volatile prices - up to $5.03 on Google Cloud. (Thunder Compute)4 That range is the story, not either end of it. Take a unit bought for $20,000, running 80% of the time over five years. The capital share alone comes to about $0.57 per hour used, before power, cooling, networking and operations. At $2.70 an hour - CoreWeave's on-demand price - revenue covers that easily. At $1.09, the cheapest on-demand price published under a provider's name, it covers it with comfortable margin. At the floor of the surplus market, where offers fall to $0.45, it doesn't cover it at all. Now change one variable. If the acquisition price were $8,000 instead of $20,000, the capital share drops to about $0.23 an hour, and the result flips at nearly all of those prices. These are illustrative figures, not a company's books; the large fleets don't publish what they actually pay. But they are enough to separate two things people routinely merge: that a machine still runs is one fact, that it has earned back its price is another. That it will fund its own successor is a third, and it doesn't follow from the first two. There is a finer distinction too. A machine can fail to recover its original cost and still be worth running today. The purchase price is spent and gone; the only live question is whether its revenue covers its power and its floor space. Except that calculation runs into a last question: what would the company have earned by putting a newer machine in the same spot? And that spot, it turns out, is not a neutral box. The Building Is Fine. The Hall Isn't. When power is the binding constraint, swapping old hardware for something that yields more value per megawatt looks obvious. The obvious move assumes the hall will take the new generation the way a warehouse takes a box. In one NVIDIA reference design, four DGX H100 systems in a single rack draw about 40.8 kilowatts. A GB200 NVL72 system reaches roughly 120 kilowatts per rack. Three times the power density in the same footprint. That jump is not executed by pulling one box out and sliding another in. You cannot cool 120 kilowatts with air. It needs liquid running to the chip, pumps, and heat exchangers. It needs new busbars inside the rack and new power distribution units, and sometimes new feed all the way back to the building. The result is a paradox that cuts both ways. A hall that cannot host the new generation gives the old hardware a kind of immunity, because keeping it running is cheaper than gutting the room. At the same time, the company may be forced to reinvest in the hall long before the building itself grows old. The concrete may serve a quarter of a century; the hall's electrical and mechanical arteries can reach the end of their economic life before the building is halfway through its own. What does that cost? Companies don't disclose a separate figure; it disappears into capital project lines. The closest published quantitative signal is a study by STL Partners, commissioned by the cooling company Airedale. It estimates converting cooling to liquid at roughly $2 million per megawatt, against more than $11 million per megawatt for a new facility built liquid-cooled from the start. (STL Partners) The two numbers do not divide into each other. The first covers cooling alone, while upgrading a hall extends to power, rack density and construction work. The second is a floor, not a point. And the study itself warns that the simple figure excludes revenue lost while the hall is out of service. (STL Partners) What remains is that facility life is a physical fact, and its price is still hidden. It is the silent difference between a long-lived building and a plant that demands recapitalization before its midpoint. Who Carries the Risk? Before we size the next cycle, there's a prior question: who can absorb it at all? The scale of replacement is unknown. How all of this is financed shows up more clearly - and it reveals that the four companies are not one bloc