SiPearl, the French chip startup founded in 2020 with a mission to build an all-European processor for sovereign AI and HPC workloads, is closing in on general availability of its Rhea1 CPU—and the timing couldn't be better. The company announced in May that it has received Rhea1 from the lab and initiated its 'bring-up' process, marking what looks like the final countdown to a late 2026 or early 2027 launch.

CPUs Are Back, Baby

Here's where SiPearl's bet on CPUs starts looking prescient: the old rule of thumb recommending one CPU for every eight GPUs has shifted dramatically. Industry recommendations now point toward a one-to-one CPU-to-GPU ratio for AI workloads. This reflects the sequential nature of many AI inference tasks, which don't parallelize as efficiently as training jobs can on GPUs. "When you have GPUs, you need to have CPUs to orchestrate the GPUs," SiPearl Founder and CEO Philippe Notton told EE News Europe. It's a point that shouldn't be lost on anyone watching this space—Nvidia itself acquired Groq's IP for $20 billion and is pushing its own ARM-based Vera CPU precisely because orchestration matters.

The Rhea1 Architecture

The Rhea1 is a monolithic ARM chip packing 80 Neoverse V1 cores manufactured by TSMC using a 6nm process. Each core includes two Scalable Vector Extension (SVE) units of 256 bits each, supporting FP64, FP32, BF16, and INT8 formats across standard compilers like C/C++, Go, and Rust, plus modern AI frameworks including TensorFlow and PyTorch. Memory-wise, Rhea1 delivers a unique mixed-memory architecture combining DDR5—up to 2TB per socket across four interfaces—and High Bandwidth Memory (HBM). The chip houses four HBM2e stacks providing 64GB with an estimated 1.8 TB/s of bandwidth. On connectivity, Rhea1 offers 104 lanes of PCIe Gen5 through the Arm Neoverse CMN-700 coherent mesh network-on-chip.

European Money, European Chips

SiPearl pledged from day one to raise only from European firms—a commitment that's paying off in both funding and geopolitical relevance. Last July, the company closed a €130 million Series A round backed by public funds including the European Investment Council Fund, France 2030, and the European Investment Bank. Corporate investors include British semiconductor firm Arm Holdings and Bull (recently separated from Atos with ambitions to revive high-end server manufacturing in Europe). Even Cathay Venture Capital from Taiwan came in with EU blessing. The strategic angle is clear: building competitive chip design capability without depending on US or Chinese supply chains.

EuroHPC Jupiter and the Road Ahead

Rhea1 will power EuroHPC's first exascale system—the Jupiter cluster module at Jülich Supercomputing Centre in Germany—featuring more than 1,300 nodes. Meanwhile, Rhea2 is already on the roadmap with a chiplet-based architecture (a departure from Rhea1's monolithic die), targeting tape-out in 2027 for installation at CEA's TGCC supercomputing center. For defense, aerospace, and government applications, SiPearl is developing Athena1—a configurable variant offering 16 to 80 Neoverse V1 cores with European packaging planned down the line.

Building a European Gigafactory

SiPearl just announced its participation in AETHER Infrastructures, an initiative aiming to construct a European gigafactory as part of the European Commission's broader semiconductor push. Planning is underway for two data centers in France's Strasbourg region (FR-SXB1 and FR-SXB2) with 42 megawatts of combined capacity. The consortium targets over 400MW of net-zero data center infrastructure featuring SiPearl processors alongside 2CRSi servers (equipped with Nvidia and AMD silicon) and Axelera AI accelerators—essentially a full European stack for demanding AI workloads.

Key Takeaways

  • Rhea1's 80 Neoverse V1 cores, HBM2e memory, and PCIe Gen5 connectivity position it for HPC and inference-heavy AI tasks
  • The shift from GPU-centric to CPU-inclusive architectures validates SiPearl's original thesis
  • €130M Series A proves European institutional money is serious about chip sovereignty
  • EuroHPC Jupiter deployment gives Rhea1 a flagship reference installation before general availability

The Bottom Line

Let's be real: Europe has been late to the semiconductor game for decades, but SiPearl's trajectory shows the continent can build competitive silicon when it commits resources. Whether €43 billion in Chips Act funding and initiatives like AETHER will be enough to challenge TSMC, Nvidia, and AMD remains an open question—but Rhea1 shipping into EuroHPC's flagship exascale system is exactly the kind of vote of confidence that could attract more talent and capital to European chip design.