Supercomputers/Systems/Castner
USA · operational · mixed
Castner
Also known as HPE Castner
Operated by Hewlett Packard Enterprise .
Phase 1 seed dataset, compiled by hand. These rows were built from public operator, laboratory and vendor sources. A mechanical second-reader pass has since fetched every cited source: 1092 of 1153 systems have a readable citation that names them, and 40 are genuinely weakly sourced. Every claim carries its source and a confidence tier. Treat anything below verified as a lead, not a citation.
Measured performance
- Rmax
- 2.92 PFlop/s
- Rpeak
- 3.54 PFlop/s
- Rmax ÷ Rpeak
- 82.5%
- Cores
- 13,056
- Power
- -
- Per watt
- - GF/W
Figures are as last publicly reported for the configuration described below, not a live measurement. Where a system was upgraded in place, the post-upgrade configuration is shown and the earlier one appears in the timeline.
What this machine is made of
One row per supplier relationship. “Supplier at build” is the company that shipped the part at the time; where that company has since been acquired, the parent it rolls up to today is shown beside it. That distinction is what makes ticker-level aggregation possible across a thirty-year dataset.
| Role | Part | Supplier at build | Quantity | Confidence | Source |
|---|---|---|---|---|---|
| Integrator | - HPE Cray EX254n | Hewlett Packard Enterprise | - | Reported | top500.org |
| Accelerator | NVIDIA GH200 Grace Hopper Superchip Accelerators Arm CPU + CUDA GPU · TSMC 4N NVIDIA GH200 Superchip | NVIDIA | - | Reported | top500.org |
| CPU | NVIDIA Grace CPUs Armv9 (Neoverse V2) · 72C · 3.1 GHz · TSMC 4N NVIDIA Grace 72C 3.1GHz | NVIDIA | - | Reported | top500.org |
| Interconnect | HPE Slingshot-11 Interconnect Dragonfly · 200 Gb/s per port · Around 2 microseconds Slingshot-11 | Hewlett Packard Enterprise | - | Reported | top500.org |
| Operating system | HPE Cray Operating System Operating systems SUSE-derived Linux, container-based management · Proprietary layer over open-source Linux HPE Cray OS | Hewlett Packard Enterprise | - | Reported | top500.org |
The read
HPE-run Grace Hopper system listed by TOP500 under Hewlett Packard Enterprise as Castner: an HPE Cray EX254n with NVIDIA Grace 72C 3.1GHz CPUs and NVIDIA GH200 Superchips on Slingshot-11 under HPE Cray OS, installed 2025, with 13,056 cores, Rmax 2.92 PFlop/s, Rpeak 3.54 PFlop/s and 41.73 TFlop/s on HPCG. It debuted at rank 436 on the November 2025 list and was 461st in June 2026. TOP500 is the only source fetched, so the tier is reported; no power figure, city or in-service date is published.
Timeline
- 2025-11 List debut at #436 (November 2025) source
Public list appearances
Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.
Change history
- 2026-10-07 Added Castner (hpe)
Source check
We fetched this system's own citations and recorded whether each page actually mentions it. This is a corroboration signal, not a fact check, and it is published so you can see how well the sourcing holds up rather than take it on trust.
| Cited source | Result | Found on the page |
|---|---|---|
| top500.org | names system and part | NVIDIA Grace, NVIDIA GH200 Grace Hopper Superchip, HPE Slingshot-11, HPE Cray Operating System |
Checked 2026-10-09 by pnpm verify. Re-run it and the table changes with the web.
Further reading
Operating a supercomputer
Acceptance testing, why "installed" and "in production" are six months apart, and the machine lifecycle.
Inside a node
Latency-optimised versus throughput-optimised processors, NUMA, and the end of the host-to-device copy.
The interconnect
Topologies, why latency and tail behaviour matter more than bandwidth, and how the fabric market consolidated.