Introduction

AMD took baby steps into the HEDT (high-end desktop) segment that eluded it for a decade, with the Ryzen Threadripper series and a modest line-up of just three SKUs. Those three were enough to plunge Intel's bloated "Skylake-X" Core X processor family into complete disarray. Intel's initial Core X family were built on the LCC (low core count) variant of Skylake-X, which has up to 10 cores. It responded to AMD's 12-core and 16-core Threadrippers with SKUs based on the HCC (high core count) die and up to 18 cores. Threadrippers continued to offer value under the $1000-mark, while Intel's HCC-based SKUs remained uncontested. AMD changed that with the 2nd generation Threadripper family which introduces the WX (workstation-enthusiast) sub-variants consisting of 24-core and 32-core models to blunt HCC.

AMD's Ryzen Threadripper processors are multi-chip modules of 8-core dies. The 16-core and 12-core models feature 2 dies, while the 24-core and 32-core ones have 4. These are both similar and dissimilar to the company's EPYC high core-count processors; similar in being 4-die MCMs, but dissimilar in the way they're wired out. Logically, an MCM with four "Pinnacle Ridge" dies must have a 8-channel DDR4 memory interface and 128 PCIe lanes. The SP3r2 package has wiring for all those. However, AMD didn't want to force users to upgrade motherboards just to have these 24-core or 32-core parts, and it probably didn't want them to cannibalize its high-margin EPYC products. So it decided to make the 4-die MCMs work on X399 by wiring memory and PCIe to just two of the four dies, while having the other two dies rely on the Infinity Fabric interconnect for memory and I/O access.



Cores on the dies with memory and PCIe wiring are called "I/O cores," while those without direct access are called "compute cores." AMD's highly customized scheduler extensions for Windows, from the Ryzen Master software, ensure that I/O cores are saturated with processing workloads first, before the compute cores. In theory, this should benefit applications that can scale beyond 16-core/32-thread, but if that workload is memory-intensive, it could drag down performance of all cores. The Ryzen Threadripper 2990WX is the company's flagship part, with 32 cores and 64 threads.

The Ryzen Threadripper 2970WX, which we're reviewing today, is 24-core/48-thread. AMD achieves this core count by disabling two cores per die. Within each die, one core per Zen Compute Complex (CCX) is disabled. The resulting CCX configuration is [3+3] + [3+3] + [3+3] + [3+3]. We wonder why AMD didn't go with full [4+4] + [4+4] for the I/O dies and [2+2] + [2+2] for the compute dies, ending up with two-thirds of its cores having direct I/O. One possible explanation is it probably didn't want I/O dies to saturate the memory bus too much, leaving the compute dies as dead weights in memory-intensive scenarios. The 2970WX offers the same clock speeds as the flagship 2990WX with 3.00 GHz stock and 4.20 GHz maximum Precision Boost frequency. This supposedly-workstation chip also has XFR (extended frequency range), which rewards good cooling with automatic overclocks beyond even the maximum boost frequency. You also get the full 64 MB of L3 cache, full quad-channel DDR4 memory interface, and full 64-lane PCIe interface.