The eleven parts that only show up above hyperscale

Every one of this catalog’s 130 top-level part categories carries a list of the facility sizes it shows up in: edge, enterprise, hyperscale_building, ai_campus, gw_class. Most parts carry most of the tiers. A GPU is a GPU whether there are eight of them in a closet or eight hundred thousand across a campus.

Eleven parts are different. They carry ai_campus and gw_class and nothing below, which in this catalog means: below campus scale, this part is not on the bill of materials at all. Not smaller — absent.

Ten of the eleven are power.

The list

Supplier counts include each part’s child categories, because several of these parents hold no companies of their own — renewables and storage is empty at the top and carries its 36 companies across seven children (solar, inverters, trackers, wind, geothermal, hydro, long-duration storage). Reading the parent row alone would report zero.

Fusion is the only part in the catalog restricted to gw_class on its own, with no ai_campus tier beneath it.

What the split is actually saying

Scale, in this catalog’s structure, does not change the rack. It changes what is outside the building.

Go from a hyperscale building to a campus and the compute layers barely move: the same accelerators, the same HBM, the same transceivers, more of them. What appears is a substation, a switchyard, and a generation strategy — the 345–765 kV transformer at the fence line, the gas-insulated switchgear behind it, and then the question of where the electricity comes from, which is what layer 8 is. Eight of the eleven parts are that question in its various answers: turbines, existing nuclear, small modular reactors, renewables and storage, the transmission system, the gas that feeds the turbines, and fusion at the far end.

The eleventh is not power. DCI and coherent optics is the long-haul link between buildings, and it appears at exactly the point where “the data center” stops being one building.

Two of the five parts this catalog flags for supply — large power transformers and gas turbines, both marked constrained — are in this group. Neither exists as a line item for anyone building below campus scale. That is worth stating plainly, because the two most-discussed schedule risks in AI infrastructure are risks that only a certain size of buyer ever encounters.

The reverse case

Fourteen parts run the whole way down to edge. Six are memory and storage — HBM, DRAM, memory modules, buffer chips, NAND, enterprise SSDs — and six are raw materials: copper, aluminum, rare earths, specialty glass, industrial gases, critical minerals. The other two are developers and operators and physical security.

That is a coherent statement: the things that scale continuously from a cabinet to a gigawatt are the commodity inputs and the chips you buy by the unit. Everything with a minimum viable size is in between.

Two cooling parts stop early in the other direction. Rear-door heat exchangers carry enterprise and hyperscale_building only, and immersion cooling stops at ai_campus without a gw_class tier. Those two are the ones to treat most carefully — see below.

What this is not

The tier lists are editorial judgment from the taxonomy, not disclosure. No supplier told us that rear-door heat exchangers do not appear at gigawatt scale, and nothing on this site sources that claim. It is a reading, and readings are the weakest thing this catalog carries. Treat the tier columns as a way to navigate 130 categories, not as evidence about any one of them.

The sourcing column in the table above is the honest measure of how much of this group rests on primary evidence: 268 placements across the eleven parts, 4 of them carrying a source URL. That is 1.5%, against 7.0% catalog-wide — the power side of the fence is the least documented region of this site, and layers 8 and 9 have not had a sourcing pass at all yet.

One thing the group is not unusual for: public ownership. 130 of the 221 companies on these eleven parts have a listing, 59%, against 56% for every company on any placement in the catalog. Building the outside of a gigawatt campus is not a notably more private business than building the inside of a rack.