A quick refresher and Dynamic Local Mode

AMD’s 2nd Generation Threadripper finally fills out

In general, the rollout of AMD's second-generation Ryzen Threadripper processors has been a bit unconventional. While the full lineup was announced back in August, there has been a staggered release period.

Later in August, we first got our hands on the Threadripper 2950X and 2990WX, the 16 and 32-core variants. Even though both of these parts were reviewed at the same time, the 2990WX was available first, with the 2950X coming a few weeks later.

Now more than two months later, we are taking a look at the 12-core Threadripper 2920X and the 24-core Threadripper 2970WX which were announced alongside the Threadipper parts that have already been shipping for quite a while now.

Will these new Threadripper processors be worth the wait?

  Threadripper 2990WX Threadripper 2970WX Threadripper 2950X Threadripper 2920X Core i9-7980XE Core i9-9900K
Architecture Zen+ Zen+ Zen+ Zen+ Skylake-X Coffee Lake Refresh
Process Tech 12nm 12nm 12nm 12nm 14nm+ 14nm++
Cores/Threads 32/64 24/48 16/32 12/24 18/36 8/16
Base Clock 3.0 GHz 3.0 GHz 3.5 GHz 3.5 GHz 2.6 GHz 3.6 GHz
Boost Clock 4.2 GHz 4.2 GHz 4.4 GHz 4.3 GHz 4.2 GHz 5.0 GHz
L3 Cache 64MB 64MB 32MB 32 MB 24.75MB 16MB
Memory Support DDR4-2933 (Quad-Channel) DDR4-2933 (Quad-Channel) DDR4-2933 (Quad-Channel) DDR4-2933 (Quad-Channel) DDR4-2666 (Quad-Channel) DDR4-2666 (Dual-Channel)
PCIe Lanes 64 64 64 64 44 16
TDP 250 Watts 250 Watts 180 Watts 180 Watts 165 Watts 95 Watts
Socket TR4 TR4 TR4 TR4 LGA-2066 LGA1151
Price (MSRP) $1799 $1299 $899 $649 $1999 $499 MSRP ($580 street)

From a specifications perspective, these new Threadripper CPUs provide little in the way of surprise. Aside from the core-count difference, there is little to differentiate these parts from the existing higher core count SKUs, even down to the clock speeds and TDPs.

Interestingly enough, both the new 2920X and 2970WX provide the same relative value propositions with a price that is 27% lower, despite losing 25% of the processing cores compared to the 2950X and 2970WX respectively. 

Dynamic Local Mode

One of the more exciting prospects of the launch of these last few second generation Threadripper CPUs today is the subsequent launch of AMD's Dynamic Local Mode.

Applying only to the WX-series Threadripper CPUs, Dynamic Local Mode is a piece of software, acting as a Windows service, which aims to reallocate cores based on a given dynamic workload.

To understand the potential advantages of Dynamic Local Mode, we must first take a quick refresher to look at how exactly the Threadripper X and WX-series CPUs are architected.

A diagram of the memory structure utilized in the Threadripper X-series processors

For the 12 and 16-core variants, the newer Threadripper CPU follow the same basic block level design we saw with the original Threadrippers. In this case, two Ryzen Pinnacle Ridge dies (equivalent to a Ryzen 7 2700X) are linked by Infinity Fabric to form the basic CPU design. Each die has access to a dual-channel memory controller, as well as 32 lanes of PCI Express. 

A diagram of the memory structure utilized in the Threadripper WX-series processors

However, with the new 24 and 32-core Threadripper CPUs, this structure is adapted slightly. Instead of connecting each of the 4 Pinnacle Ridge CPU dies to a memory controller and PCI Express controller as we see in AMD's EPYC server chips, more of a hybrid approach is taken here. 

Instead, Infinity Fabric links are used to connect every given Core Complex (CCX) to another, while maintaining two total memory controllers, and 64 lanes of PCI Express. This means, that for some cores to access the memory or PCI Express connectivity, they must first communicate over Infinity Fabric to another CCX, adding significant levels of latency.

Given Windows' lack of awareness of this unique memory structure, we found in our initial review of the Threadripper 2990WX that performance can be substantially impacted by this sort of memory access latency in some applications. Others have found that with Linux, which is substantially more adaptable and aware of non-standard memory configurations, the 2990WX performed much better than in Windows.

Dynamic Local Mode is AMD's attempt to fix this issue, without having access to fix it at its core, the Windows Scheduler level. Instead, Dynamic Local Mode works in the background to shuffle around CPU and memory heavy processes to threads that have direct memory access.

This feature can be enabled and disabled on the fly in the newest version of AMD's Ryzen Master desktop software.

Given the substantial changes that Dynamic Local Mode has to offer, we will be testing it on both the 2990WX and 2970WX alongside the stock configuration in all tests for this review.

Review Terms and Disclosure
All Information as of the Date of Publication
How product was obtained: The product is on loan from AMD for the purpose of this review.
What happens to the product after review: The product remains the property of AMD but is on extended loan for future testing and product comparisons.
Company involvement: AMD had no control over the content of the review and was not consulted prior to publication.
PC Perspective Compensation: Neither PC Perspective nor any of its staff were paid or compensated in any way by AMD for this review.
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