Three tranches of 220,000
Elon Musk posted a build-out schedule for Colossus 2, the SpaceXAI computing cluster near Memphis, on X early on Friday 25 September. It is the most specific timetable the company has given.
By Musk’s own account, the site currently runs 110,000 Nvidia GB200 chips and 440,000 GB300s — 550,000 in total. A further 220,000 GB300s are due to be operational next week, another 220,000 in November, and a third 220,000 in late December “if we get lucky”.
If all three land, Colossus 2 ends the year at 1.21 million GB200 and GB300 processors, of which 1.1 million would be GB300s. That is more than double what is running now.
Musk explained the odd base number in a reply: the multiple of 110,000, he wrote, comes from the number of fibre optic cables that can be plugged into a central switch.
The part he did not address
Reuters noted that Musk did not specify whether Colossus 2 has enough readily available capacity and power to run the additional chips. That is the question the schedule turns on. A GB300 rack is not limited by how many are shipped but by how much electricity and cooling is standing by when they arrive.
It is also the reason the final tranche is hedged. “If we get lucky” is doing real work in a sentence about 220,000 accelerators arriving in the last weeks of a year.
What Colossus is for
The original Colossus was built in 2024 and has been described as the largest AI supercomputer in the world. The complex no longer serves only its owner: SpaceXAI rents computing capacity from it to other companies, including Anthropic and Alphabet’s Google.
That matters to how the number should be read. A cluster that sells capacity is not purely a measure of one lab’s training ambition; part of the build-out is a hosting business.
Why the figure is worth recording
Chip counts at this scale are one of the few public, checkable proxies for how much frontier compute a lab actually commands. They are also routinely stated by the people with the strongest interest in the number being large, which is why the source matters: this is Musk’s own figure for his own site, not an independent count.
The near-term part of it is testable. Musk says 220,000 GB300s come online next week. That is a claim with a date on it.
What to watch
Whether the first tranche lands on schedule, and whether SpaceXAI says anything about the power arrangements behind the second and third. The December tranche is the one to treat as provisional until it is running.
