Refresh cadence and silicon generation decay

The headline is how long generations last, and it is longer than the release cadence suggests. Vendors ship a new accelerator every eighteen months to two years; the installed base turns over on something closer to a seven-to-ten-year cycle. Kepler's K20X entered service in 2012 and was still running in 2021. The gap between those two clocks is where most of the confusion about “refresh cycles” lives: a procurement cycle and a product cycle are not the same cycle.

The second pattern is the release-to-deployment lag. Parts do not appear in leadership systems the year they launch; the median here is a year, and the exceptions run longer. That lag compounds with the announcement-to-first-light lag on the schedule page: a system announced around silicon that has not shipped is committing to two uncertainties at once.

The third is displacement, and the clearest case is not a technical one. Intel's Xeon Phi 31S1P has a closed span ending in 2018, and it did not end because something faster arrived: it ended because an export control blocked the upgrade path and NUDT substituted its own part. On this chart that is a generation dying at a policy boundary rather than a performance one, which is exactly the kind of thing a supply-chain view can show and a ranking cannot.

The bars at the right-hand edge are all open, which is the correct rendering and also the limitation. Every current generation looks short-lived because it has not finished yet. Nothing on the right third of this chart should be read as a lifespan.