Supercomputers/Systems/Isambard-AI Phase 2
United Kingdom · operational · ai training
Isambard-AI Phase 2
Deep dive: Isambard-AI versus Alps: two GH200 routes
Operated by University of Bristol at National Composites Centre, Bristol .
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
- 216.5 PFlop/s
- Rpeak
- 278.6 PFlop/s
- Rmax ÷ Rpeak
- 77.7%
- Cores
- 1,028,160
- 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 EX4000 | Hewlett Packard Enterprise | - | Reported | top500.org |
| Accelerator | NVIDIA GH200 Grace Hopper Superchip Accelerators Arm CPU + CUDA GPU · TSMC 4N NVIDIA GH200 Superchip | NVIDIA | - | Verified | top500.orgbristol.ac.uk |
| CPU | NVIDIA Grace CPUs Armv9 (Neoverse V2) · 72C · 3.1 GHz · TSMC 4N NVIDIA Grace 72C 3.1GHz | NVIDIA | - | Verified | top500.orgbristol.ac.uk |
| Interconnect | HPE Slingshot-11 Interconnect Dragonfly · 200 Gb/s per port · Around 2 microseconds Slingshot-11 | Hewlett Packard Enterprise | - | Reported | top500.org |
| Storage | HPE Cray ClusterStor E1000 Storage Lustre appliance, flash and disk tiers · 700 PB on Frontier (Orion) · About 10 TB/s peak 20 PiB Cray ClusterStor, all solid-state | Hewlett Packard Enterprise | - | Reported | bristol.ac.uk |
| Storage | VAST Data Platform Storage Disaggregated shared-everything 3.5 PiB VAST, all solid-state | VAST Data | - | Reported | bristol.ac.uk |
| Cooling | Direct liquid cooling, warm water Cooling Direct-to-chip cold plates, facility water loop · Removes 90+ percent of node heat to liquid Direct Liquid Cooling | Hewlett Packard Enterprise | - | Reported | bristol.ac.uk |
| 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 |
AI datacenter metrics
Figures beyond an accelerator count, each with who stated it. What can and cannot be compared across AI datacenters.
| Metric | Value | As of | Basis | Note | Source |
|---|---|---|---|---|---|
| Accelerators | 5,280 accelerators | 2026-10 | Operator stated | Phase 2 only: 1,320 nodes x 4 GH200. Bristol says the combined Isambard-AI total is 5,448 superchips. | docs.isambard.ac.ukbristol.ac.uk |
| Facility power | 5 MW | 2026-10 | Operator stated | Grid supply at the National Composites Centre site, covering Isambard-AI as a whole (both phases). ITPro reports it as the site draw. | itpro.com |
| PUE | 1.08 | 2026-10 | Operator stated | Bristol states 'around 1.08' for the modular data centre (direct liquid cooling); ITPro reports 1.1. Covers the whole site. | bristol.ac.ukitpro.com |
The read
The expansion that took Isambard-AI from a 34,272-core pilot to one of Europe's largest GPU fleets: 5,280 more GH200 superchips on the same Bristol site, bringing the combined total to 5,448. TOP500 carries phase 1 and this phase as two separate system entries with two separate HPL submissions rather than one upgraded machine, and this dataset follows that split rather than merging them.
Timeline
Public list appearances
Pointers only: rank and edition, linking to the canonical entry. We do not reproduce list tables. See sourcing policy.
Site & facility
National Composites Centre, Bristol
- Location
- Bristol, United Kingdom
- Cooling
- Direct liquid cooling
- Commissioned
- 2024
Change history
- 2026-10-04 Added AI datacenter metrics for isambard-ai-phase2
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 GH200 Grace Hopper Superchip, NVIDIA Grace, HPE Slingshot-11, HPE Cray ClusterStor E1000, HPE Cray Operating System |
| bristol.ac.uk | names system and part | NVIDIA GH200 Grace Hopper Superchip, NVIDIA Grace, HPE Cray ClusterStor E1000, VAST Data Platform, Direct liquid cooling, warm water, HPE Cray Operating System |
Checked 2026-10-09 by pnpm verify. Re-run it and the table changes with the web.
Related news
- Isambard-AI phase 2 goes live as the UK's most powerful AI supercomputer · NVIDIA Blog5,448 GH200 superchips across a purpose built 5MW facility that went from conception to operation in about two years, reported as more than ten times faster than the next UK system at the time. It is the clearest UK entry in this dataset's post-2023 Grace Hopper wave alongside LUMI and Alps.
Further reading
Inside a node
Why accelerators exist, what the memory hierarchy costs, and how the CPU and accelerator merged onto one package.
The interconnect
Topologies, why latency and tail behaviour matter more than bandwidth, and how the fabric market consolidated.
Operating a supercomputer
Acceptance testing, why "installed" and "in production" are six months apart, and the machine lifecycle.