Intel Clearwater Forest Xeon: More cores, more performance – thanks to Foveros Direct 3D stacking

The Clearwater Forest CPUs are expected to be launched on the market in mid-2024 as the successor to the Sierra Forest Xeon chips. Both chips have one thing in common: the use of E-cores instead of P-cores. The E-cores used in the Sierra Forest chips are codenamed Sierra Glen and are modified versions of the Crestmont core architecture. The Darkmont cores used in the Clearwater Forest chips, on the other hand, are based on slightly modified versions of the Skymont cores.

There is recent information indicating that Intel plans to fully utilize its hybrid bonding technology called Foveros Direct to integrate the Clearwater Forest Xeon CPUs into 3D stacking. The CPU package will consist of a base tile placed on the interposer and connected via a high-speed I/O, EMIB. The cores will be located on the top layer.

Intel’s Foveros Direct technology enables direct copper-to-copper bonding, which allows for low resistive connections and bump spacing of about 10 microns. According to Intel, Foveros Direct blurs the boundary between the end of the wafer and the beginning of the package. The technology was originally expected to be ready for production by the second half of 2023, but the timeline has since changed.

It will be interesting to see how the implementation of 3D stacking (Foveros Direct) will be realized in the Intel Xeon E-Core family. The Clearwater Forest chips should offer up to 288 cores and 288 threads and deliver significant improvements in IPC and efficiency. Another important point is the increase in cache on the package. It is possible that the base stack itself contains additional cache pools that are directly connected to the cores on the top layer. The Xeon Clearwater Forest CPUs are expected to launch in 2025, but more information can be expected tomorrow during Intel’s IFS direct keynote.

Source: @SquashBionic