Japan · operational · ai training

MN-3

Operated by Preferred Networks at Preferred Networks (Yokohama) .

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: 2.18 PFlop/s
Rpeak: 3.35 PFlop/s
Rmax ÷ Rpeak: 65.1%
Cores: 1,664
Power: 53.29 kW
Per watt: 40.9 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	- MN-Core Server, self-built by Preferred Networks	Preferred Networks	-	Reported	preferred.jp top500.org
Accelerator	Preferred Networks MN-Core (1st generation) Accelerators TSMC 12nm · 500 W Preferred Networks MN-Core, 128 processors used in the record-setting Green500 run	Preferred Networks	128 reported	Verified	preferred.jp top500.org
CPU	Intel Xeon Platinum 8260M (Cascade Lake) CPUs x86-64 · 24C · 2.4 GHz Xeon Platinum 8260M 24C 2.4GHz	Intel INTCNASDAQ	-	Reported	top500.org projects.preferred.jp
Interconnect	MN-Core DirectConnect Interconnect 112 Gb/s per link MN-Core DirectConnect	Preferred Networks	-	Reported	top500.org projects.preferred.jp

The read

The only system in this dataset whose accelerator role is filled by neither NVIDIA nor AMD: MN-Core is a deep-learning ASIC that Preferred Networks co-developed with Kobe University, built around a matrix-arithmetic grid with no conventional cache hierarchy or branch prediction. MN-3 topped the Green500 list four times running, June 2020, November 2020, June 2021 and November 2021, reaching 39.38 GFlops/Watt on its last win, all in a window before this dataset's Green500 tracking otherwise begins in November 2023, which is why the rank pointer here targets the November 2021 edition specifically. Preferred Networks' own release and TOP500's independent Green500 listing agree on the rank, efficiency and power figures, so the tier is verified. Its current operational status has not been independently confirmed since its last public TOP500 appearance in mid 2024; we carry the last documented state rather than inferring a retirement.

Timeline

2020 Announced source
2020-05 First operational source
2021-11 List debut at #1 (November 2021) source

Public list appearances

Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.

Site & facility

Preferred Networks (Yokohama)

Location: Yokohama, Japan
Commissioned: 2020

top500.org projects.preferred.jp

Change history

2026-09-24 MN-3 added (Preferred Networks, Japan)

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 8260M (Cascade Lake), Preferred Networks MN-Core (1st generation), MN-Core DirectConnect
preferred.jp	names system, part and count	Intel Xeon Platinum 8260M (Cascade Lake), Preferred Networks MN-Core (1st generation), MN-Core DirectConnect · counts: 128

Checked 2026-10-09 by pnpm verify. Re-run it and the table changes with the web.