Supercomputers/Systems/Oakbridge-CX
Japan · decommissioned · hpc
Oakbridge-CX
Operated by University of Tokyo .
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
- 4.29 PFlop/s
- Rpeak
- 6.62 PFlop/s
- Rmax ÷ Rpeak
- 64.8%
- Cores
- 76,608
- Power
- 845.09 kW
- Per watt
- 5.1 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 | - Fujitsu PRIMERGY CX2550/CX2560 M5, 1,368 nodes | Fujitsu | - | Reported | top500.orgcc.u-tokyo.ac.jp |
| CPU | Intel Xeon Platinum 8280 CPUs x86-64 · 28C · 2.7 GHz · 14 nm · 205 W Two Intel Xeon Platinum 8280 28C 2.7GHz per node | Intel | - | Verified | top500.orgcc.u-tokyo.ac.jp |
| Interconnect | Omni-Path Architecture Interconnect Fat tree · 100 Gb/s per port · About 1 microsecond Intel Omni-Path 100 Gbps | Intel | - | Verified | top500.orgcc.u-tokyo.ac.jp |
The read
The University of Tokyo Information Technology Center's Fujitsu PRIMERGY cluster of 1,368 nodes (1,240 standard and 128 with SSD), each with two Xeon Platinum 8280 (28-core) CPUs and 192 GiB memory on 100 Gbps Intel Omni-Path. The centre quotes 6.61 PFlop/s peak; TOP500 lists 76,608 cores, Rmax 4.29 and Rpeak 6.62 PFlop/s at 845 kW, debuting 45th in June 2019 and last listed in June 2023. The centre's service page states operation has been terminated; the exact end date was not found.
Timeline
Public list appearances
Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.
Change history
- 2026-10-02 Added Oakbridge-CX, the University of Tokyo Omni-Path cluster, 45th on the June 2019 TOP500
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 | Intel Xeon Platinum 8280, Omni-Path Architecture |
| cc.u-tokyo.ac.jp | names system and part | Intel Xeon Platinum 8280, Omni-Path Architecture |
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.