French chip designer SiPearl has delivered the first samples of its Rhea1 CPUs to high-performance computing (HPC) firm Bull.

Following the delivery, Bull has begun integrating Rhea1 into its BullSequana XH3000 platform, which forms the basis for Europe’s first exascale supercomputer, Jupiter.

The deal represents the first order for SiPearl’s Rhea1 processors, and therefore constitutes the first significant revenue for the company.

Rhea1 will power the CPU cluster of the Jupiter supercomputer, hosted at the Jülich Supercomputing Centre (JSC) Forschungszentrum Jülich campus in Germany. Procured by the EuroHPC Joint Undertaking (EuroHPC JU), Jupiter is Europe’s first exascale supercomputer, with Jupiter Booster, a partial version of the larger supercomputer, ranking fifth on the most recent edition of the Top500 list of the world’s most powerful supercomputers.

Made using TSMC’s 6nm N6 process, the CPU features 80 Arm Neoverse V1 cores, with each core comprising two 256-bit Scalable Vector Extensions, which SiPearl says will optimize area and energy use.

Rhea1 also has four stacks of HBM2E (High Bandwidth Memory) to support high-performance computing, big data, and AI inferencing applications; and four DDR5 interfaces, supporting 2 DIMMs (Dual In-Line Memory Modules) per channel. SiPearl completed the tape-out of Rhea1 in July 2025.

According to SiPearl, during ongoing benchmarking phases at the company’s laboratories, the chip is delivering a “very encouraging performance … and in some cases, performance is exceeding expectations.” Those figures will be published in the fall, SiPearl said.

“This key milestone is the result of a long-term and strategic collaboration between two European tech players, federating a stronger HPC and AI ecosystem,” said Bruno Lecointe, head of HPC, AI and quantum at Bull. “With the arrival of the first Rhea1 CPUs and their integration into our BullSequana XH supercomputing platform, our ambition is becoming reality. Integrating a European processor onto a European platform for Europe’s flagship exascale system is a milestone we can all be proud of, and a powerful demonstration of what we can achieve together when vision is matched with execution.”

Philippe Notton, CEO and founder of SiPearl, added: “Together with Bull, our long-standing partner, we are taking a major step towards Europe’s digital sovereignty by equipping the CPU cluster of the European exascale supercomputer Jupiter with European hardware. This will be a first in Europe.”

Launched in 2020 under the European Processor Initiative, SiPearl developed the Rhea1 processor, an Arm-based CPU designed to power supercomputers.

In July 2025, the company closed a €130 million ($148m) Series A financing round that saw participation from existing investors, the European Innovation Council Fund, and the French State, via French Tech Souveraineté, and new investor Cathay Venture.

The chip designer has also developed a “bespoke version” of Rhea1 dubbed Athena1, which includes sophisticated encryption and security capabilities to support the workloads of government, defense, and aerospace applications. That chip is expected to be available in the second half of 2027.