Product Lineup

Specifications

Overview

The Cerebras CS-4 is the company's first true rack-scale system, replacing the CS-3 (a single-wafer, 16U liquid-cooled unit) with a modular architecture that houses three WSE-3 Turbo wafers in a single rack — delivering 750 PFLOPS of sparse FP16, 132 GB of on-wafer SRAM, and 160.5 PB/s of aggregate fabric bandwidth.

At the heart of the redesign is the Nexus platform, a highly modular, multi-generation rack that places power supplies, fans, and supporting hardware at the front and the wafers at the rear. Each WSE mounts in a self-contained, vertically-standing backpack that connects it to the rack's power and liquid-cooling loops plus the wafer I/O modules housing the networking — decoupling networking hardware from the wafers so it can be upgraded independently. Cerebras has already committed Nexus as the basis for the upcoming CS-5 and CS-6 systems.

For scale-up/scale-out networking, the initial CS-4 uses RDMA over Converged Ethernet v2 (RoCEv2), with UALink or Ultra Ethernet as likely future options. An optional chained topology links backpacks directly without switches to minimize wafer-to-wafer latency to 2 microseconds. Compared to the CS-3, the CS-4 delivers roughly six times the per-system performance — three times the wafers, each running twice as fast.