Mining machines are frequently retired while still functioning. The reason is economic rather than mechanical: a competitor's newer hardware makes the same electricity produce more work.
Efficiency is the competitive variable
An ASIC is measured by how much computation it performs per unit of energy consumed. That ratio determines the electricity cost of each unit of revenue.
Two machines producing identical output can have very different operating costs, and in a competitive market the higher-cost machine is the one that stops first.
Improvements come from smaller semiconductor process nodes and from chip design refinements, both of which arrive in generational steps rather than continuously.
Each generation therefore resets the competitive floor at once. A machine that was near the front of the fleet becomes mid-tier the moment a substantially more efficient model ships in volume.
Why the market squeezes older units
When more efficient machines are deployed, network difficulty rises and revenue per unit of computation falls for everyone.
Older machines cross their break-even point first, because their electricity cost per unit of revenue is highest.
They are not broken at that moment. They are simply unprofitable at prevailing power prices, which is a different condition entirely.
Power price determines the retirement date
A machine unprofitable at one electricity rate can remain profitable at a lower one, so older hardware migrates toward cheaper power.
This is why secondhand machines find buyers in regions with inexpensive electricity long after being retired from higher-cost sites.
The same logic supports seasonal and interruptible operation, where older units run only during periods when power is cheapest.
Accounting rarely matches the physical life
Operators depreciate machines over a period reflecting expected economic usefulness, which is considerably shorter than the hardware's likely operating life.
Estimating that period requires assumptions about future difficulty and future hardware releases, neither of which is knowable in advance.
Assumptions that prove optimistic produce impairment charges when equipment loses value faster than the schedule anticipated.
Residual value is thin and cyclical
Retired machines retain value only as long as somewhere exists with electricity cheap enough to run them, which is a shrinking pool as efficiency improves.
Secondhand prices therefore fall sharply during downturns, precisely when operators most want to sell, and recover when revenue conditions improve.
Components have limited salvage value because the chips are purpose-built and cannot be repurposed, so end-of-life disposal is a real cost rather than a source of recovery.
Power supplies, racking and control boards are the parts that retain some resale demand. The hashing boards, which represent most of the original purchase price, generally do not.