Intel Displays Granite Rapids CPUs as Specs Leak: Five Chiplets

Intel this week showcased its 6th Generation Xeon Scalable ‘Sapphire Rapids’ processors as part of its advanced packaging prowess demonstration. The multi-tile datacenter CPU are due to arrive in the first half of 2024 and the company is sampling them with its customers. Meanwhile, hardware leaker @Yuuki_AnS this week revealed specifications of ES1 samples of these processors. 

Intel’s 6th Generation Xeon Scalable ‘Granite Rapids’ processor employs a disaggregated design with five chiplets: three tiles carrying Performance cores with 2MB of L2 cache, 4MB of L3 cache, and four DDR5 interfaces as well as two high-speed input/output (HSIO) tiles. These the most sophisticated Granite Rapids CPUs are projected to feature 12 DDR5 memory channels supporting DDR5-6400 and MCR DIMMs, 136 PCIe Gen5 lanes with CXL 2.0 support, and up to six UPI links. 

Intel has not officially disclosed the core count on the Granite Rapids CPUs, but according to the leak ES1 samples with an eight-channel memory subsystem (i.e., they carry two chiplets) top at 56 cores with 288MB of cache, which suggests that each tile carries either 28 or 30 cores and two cores per chiplet are disabled for redundance. That said, it is plausible to expect production Granite Rapids CPUs to feature 84 – 90 cores. These cores operate at 1.10 GHz – 2.70 GHz depending on the exact model, which is low, but we are talking about engineering samples of the CPUs.

The compute chiplets are made on Intel 3 (3nm-class) process technology, whereas HSIO chiplets are fabbed on a 7nm-class production node, which is a proven technology and is considered to be optimal for modern I/O chiplets in terms of performance and costs. 

Images of Granite Rapids CPUs published by Intel clearly show that the package positions the two HSIO dies at its top and bottom, while the compute dies are situated in the middle. These are all interconnected using an undefined quantity of EMIB (Embedded Multi-Die Interconnect Bridge) links embedded in the substrate. 

Intel’s Granite Rapids platform supports from one to eight sockets in a single server. Meanwhile, currently Intel is only sampling one 8S-capable Granite Rapids CPU, according to the leak.