Nothing personal: US government wants to shove 10 million Gigabytes RAM in a ‘computer’ to do ‘3D simulation’


  • US DOE seeks to purchase 20MW super computer to maintain its nuclear stockpile better
  • ATS-5 is expected to launch in 2027 and will take over HPE Intel’s based ATS-3
  • It will have at least 10PB of compute memory, the largest amount ever seen in a single device

The US Department of Energy is preparing to deploy a massive supercomputer called ATS-5 in 2027.

The system, which is designed to advance national security efforts by supporting nuclear stockpile management, marks a shift into what the DOE describes as the “post-exascale” computing era.

It will be installed at Los Alamos National Laboratory, and replace the existing 30-petaflop Crossroads (ATS-3) supercomputer. The Cray HPE Crossroads debuted at number 24 in the Top500 list in November 2023, but is now ranked 43.

Hero simulations

ATS-5 will be capable of handling massive 3D simulations essential for the National Nuclear Security Administration’s (NNSA) stockpile stewardship program, and help to manage the US nuclear arsenal – hopefully with a better sense of caution than WarGames’ WOPR supercomputer.

The system will feature a staggering 10 petabytes of compute memory in a single machine, and is projected to run within a 20-megawatt power envelope.

Designed as a mixed-architecture machine, ATS-5 will feature a combination of CPUs and GPUs, with the DOE pushing for architectural diversity. Flexibility is reportedly central to its design, with a modular architecture enabling hot-swappable compute modules, memory, and accelerators to keep up with ever-evolving technologies during the machine’s lifetime.

A key goal for ATS-5 is reducing “time-to-solution,” the time required for complex simulations to deliver meaningful insights. The system will tackle some of the largest-scale 3D simulations, known as “hero” simulations, reducing the completion time for tasks that previously took months to just days.

ATS-5 will also have the capacity to run multiple such hero simulations simultaneously, improving efficiency for critical defense analysis tasks such as modeling aging warhead materials, production techniques, and flight dynamics.

The DOE has already set performance milestones for ATS-5, reportedly seeking a 10x improvement over Crossroads in both single-node and system-wide scaling for critical workloads. This does not mean raw power but rather faster simulation scaling and greater efficiency. Memory performance, in particular, is a key focus, with the system aiming to overcome the “memory wall” by improving bandwidth and latency.

ATS-5 will be delivered in late 2026, with full benchmarking expected by the third quarter of 2027. It will run a Linux-based operating system with open-source software at its core, although HPCWire reports support for CUDA will be considered if Nvidia is selected as the vendor.

Other potential contenders to help build ATS-5 include HPE, which has experience in supercomputing projects with its Slingshot interconnect technology, used in Frontier and El Capitan, and Intel, which has an ongoing quantum project at Argonne National Laboratory.

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