AMD Ryzen Threadripper 2970WX and 2920X
ZEN+ and 12nm
The Ryzen Threadripper 2 processors carry over all the advancements introduced with second-generation Ryzen earlier in 2018. The improved Zen+ 12nm process means better power efficiency, which along with improved memory support and lower cache latency means better performance clock for clock. Add to this the higher clock rates and we have a nice bump in performance. The maximum official memory support is now DDR4-2933. AMD bin and select the best dies for Threadripper CPUs. This means lower voltage for a given clock rate, leading to better XFR and Precision Boost 2.0 along with generally better overclocking capabilities.
From the outset, AMD designed Ryzen to be modular, with basic building blocks able to be joined together to create higher core count models. AMD calls this building block ‘Zeppelin’ and it is this block that makes up the Ryzen series. Join two together and you get the 2920X and 2950X. The 2970WX and 2990WX make use of four of these blocks. The individual blocks or dies are linked together with what AMD calls ‘Infinity Fabric’. This bus allows data exchange between different core complexes, memory and I/O. Infinity Fabric is also present in Vega GPUs, so we are likely seeing the first stages of an eventual transition to multi-chip modules featuring ‘chiplets’ glued together with Infinity Fabric links. Interesting stuff.
AMD does some other interesting things with Threadripper’s memory implementation, in both first and second generations. Very high core-count CPUs and MCM (multi-chip module) designs are going to face unique challenges going forward, especially considering the lack of multi-core awareness in many applications. They’ve introduced two memory modes designed to allow memory bandwidth sensitive applications to have optimal access to the memory subsystem. There’s the UMA (distributed) mode and NUMA (local) mode. Generally UMA is best with highly threaded applications, while NUMA is better for lightly threaded apps, including games which benefit from low latency memory access. We hope to examine the effect of these options, along with overclocking, when we've had more time to explore and experiment with this architecture.
AMD implements dynamic power states and automatic clockspeed modes by reacting to a series of monitored parameters under the umbrella name ‘SenseMI’. Essentially this is a grid of interconnected sensors that poll various parameters including amperage, voltage, wattage, temperature and clock frequency with a very fine degree of precision at a polling rate of 1000 times per second. The CPU then uses this data for fine tuning the Precision Boost 2 curve, including the Extended Frequency Range (XFR) which is like a super turbo mode. It allows the frequency to increase beyond the standard turbo boost limit when power and thermal conditions allow.
Note this is the diagram for the 2990WX, but the principle is the same
Precision Boost 2 is very much improved over Precision Boost 1 from the first-generation Threadripper. AMD used the example of the game DOTA 2, which makes use of many cores but does not tax them heavily. Precision Boost 2 is able to recognize a situation like this. This means the CPU knows when it is not fully loaded, such as when all cores are utilized at only 25 or 50%. It is then able to boost to higher levels while staying within the TDP limits. Previously, if such a load was detected, the CPU would revert to its base clock, hurting overall performance.
Threadripper 2 introduces additional power management functionality termed PBO, or Precision Boost Overdrive. This allows the user to override the default platform allowances to deliver more performance. It can be set from within the Ryzen Master app. Offering this kind of functionality is an example of how AMD tends to be friendly towards tweakers and overclockers.
Note that this CPU series isn’t really aimed at gamers. Even AMD themselves make this point. Gamers will generally see no benefit at all over the likes of a Ryzen 2600 or 2700. This is in some ways due to restrictions placed upon the software developers, however. They need to make their games playable with the dual- and quad-core CPUs that power the vast majority of current gaming PCs, and probably will do for several years to come.
X399 Soldiers On
Threadripper 2 is drop-in compatible with all existing X399 motherboards after a BIOS update, negating the need for an additional motherboard purchase. All of the extensive expandability and connectivity options available with X399 carry over. Perhaps most noteworthy is the availability of 64 PCIe 3.0 lanes meaning there’s enough bandwidth on hand to handle complex SSD arrays, networking and multi GPU configurations without having to consult the motherboard manual to see what works if you add this or install that. Unlike what we see with Intel’s Skylake-X models, the maximum number of PCIe lanes are available with all Threadripper 2 CPUs. AMD deserve credit for not artificially segmenting their products. Intel’s neutering of its Skylake-X CPUs was deeply unpopular and it has reponded by unlocking all PCIe lanes across its upcoming Basin Falls refresh range.
X399 supports overclocking across the entire range, quad channel memory, up to 12 SATA ports, up to 14 native USB 3.1 ports and NVMe RAID. It remains a highly expandable platform and AMD really do deserve kudos for extending the lifespan of this platform across multiple generations. This is something Intel could take a lesson from.
AMD’s Ryzen Master is a very useful app with lots of information and settings available to tweak. Clock speeds, voltages and DRAM settings are all adjustable. It closely resembles the Radeon driver control panel. While most users will still use the BIOS for serious tweaking, Ryzen Master has a particularly important toggle: Game Mode.
As many game engines simply cannot handle very high core counts, Game Mode or Legacy Compatibility mode disables half or three-quarters of the available cores. Game testing shows a real mixed bag as we’ll see. To get the best gaming performance out of Threadripper, you really should enable Legacy Compatibility mode. According to AMD it can boost game performance by 5 to 10% in most games.
Another of the cool features is the fastest core detection. It identifies the strongest cores which you could then use for apps that require the highest clock speeds.
On to the next page, for application and gaming benchmark results.
Page 1: Introduction and Packaging
Page 2: Features, X399 Chipset, Ryzen Master
Page 3: Benchmarking Setup and Results
Page 4: Temperatures, Power, Conclusions
All original content copyright James Rolfe.
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