AMD Ryzen Threadripper 2970WX Review 21

AMD Ryzen Threadripper 2970WX Review

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Value and Conclusion

  • The AMD Ryzen Threadripper 2970WX is available for $1,300.
  • 24-core, 48-thread
  • Incredible rendering performance
  • Upgrade path to 32 core/64-thread TR 2990WX available
  • Precision Boost Overdrive simplifies overclocking
  • Works on existing Threadripper motherboards
  • Unlocked multiplier
  • Greatly improved Boost behavior compared to first generation
  • Same clocks as 2990WX
  • Extremely energy efficient for multi-core workloads
  • 64 PCIe lanes
  • Lower application and gaming performance than Threadripper 2950X
  • Low single-threaded performance
  • Suitable only for a very narrow range of applications
  • Issues in Far Cry 5
  • High effective price
  • Requires quad-channel memory for optimum performance
Threadripper 2970WX is the company's second-biggest Ryzen Threadripper, offering a staggering 24 cores and 48 threads. In terms of clock speeds, the CPU matches 2990WX specs: 3.0 GHz base and up to 4.2 GHz boost, which is rare. Normally, lower SKUs come with some kind of clock frequency reduction as an additional performance dial for the vendor to justify pricing of the more expensive model. It's also great that AMD has managed to make these new WX CPUs run on the existing X399 platform, which of course comes with some gotchas.

The biggest of these is memory. Half the cores have a direct path to the memory, half don't. The ones that don't, which AMD likes to call "compute cores," which comes across as "less than cores" or "not quite cores," are significantly deprived of memory bandwidth. Since this is a four-die multi-chip module instead of two-die, like the 2950X, the inter-die bandwidth is reduced to 25 GB/s bi-directional. If this processor is tasked with memory-intensive workloads in which all 24 cores are trying to process a lot of data, the compute cores face the first bottleneck at the inter-die Infinity Fabric link (with 25.6 GB/s; bandwidth comparable to single-channel DDR3-1600), and the second bottleneck at the narrow, effectively dual-channel interface of the I/O die. That's how bandwidth-starved these "compute" cores are.

When looking at performance numbers across the board, the Threadripper 2970WX disappoints. In nearly all of our tests, we see the Threadripper 2950X faster despite its 8-core, 16-thread disadvantage. Looking at averages, the 2970WX ends up around 10% slower than the 2950X, roughly matching the 2920X we reviewed just yesterday. Taking a closer look at the individual results, we see the 2970WX having a pretty impressive lead in rendering (Blender and Cinebench), but in other, even highly parallelized use cases, it falls behind. The reason for that is the memory interface configuration, which was the only choice for these CPUs to fit on the existing X399 platform.

AMD has just launched a new software feature for Threadripper WX, called "Dynamic Local Mode", which comes in the form of a small and lightweight Windows Service that continuously checks the CPU usage of all processes in the system. It then "sorts" these processes on to the CPU cores in a way that pairs busy apps with CPU cores that have memory attached directly to them and moves less busy programs on to cores that have no local memory. Some of our tests show good gains from that method; for example, our Java benchmark sees a 15% performance improvement. Some games also benefit from Dynamic Local Mode, such as Assassin's Creed Origins; notorious for its CPU usage, it gains 36% (but still ends up slightly slower than on the TR 2950X). Still, the majority of our applications and games don't see very big improvements because of the following issue: Most programs are either mostly single-threaded, and usually end up on the right CPU anyway, and the heavily multi-threaded applications keep all CPU cores busy, so Dynamic Local Mode has no "unused" cores to move threads away from, resulting in no net difference, just a randomized shuffle between CPU cores. Still, the concept sounds excellent, especially since it saves you the reboot you'd previously have to do to switch to Local Mode. I'm sure AMD is putting in more work for Dynamic Local Mode, maybe some predetermined application profiles could help, for signal hints on how applications could be better mapped to cores.

For their second generation of Ryzen, AMD has greatly improved the boost clock behavior of their architecture. Where previously, the frequencies would fall off a cliff as soon as more threads are active, the drop is now much more gradual, yielding higher performance for those cases. The Threadripper 2970WX retains its highest boost of 4.2 GHz for up to three completely busy threads, and then slowly reduces clock frequencies. Even with all cores fully loaded, we saw 3.55 GHz, which is still significantly higher than the 3.0 GHz base clock frequency.

With a rated TDP of 250 W, the Threadripper 2970WX is not only power hungry, but also needs good cooling. Your best option for that is watercooling. Threadripper support on all-in-one watercooling is quite good, and it won't be hard to find a cooler that will match your requirements. Unless you're planning on doing heavy overclocking, a 240 mm AIO will be perfectly fine and still has enough headroom to bump up performance using Precision Boost Overclocking. PBO is the new recommended method to overclock all second-generation Ryzen processor, including Threadripper. Instead of setting a fixed clock frequency at a fixed voltage, you now tell the CPU how much cooling you have available and how much current the VRMs on your motherboard can deliver, and PBO will automagically do the right thing, running the processor at higher clocks than default while still scaling down clock (and power usage) when the system isn't as highly loaded—all while ensuring the system will never crash.

The Threadripper WX processors are hence only suited for workloads that are heavier on math and lighter on memory, such as rendering, and not memory-intensive workloads such as video transcoding, which not just hits the Infinity Fabric bottleneck, but also strains the already narrow dual-channel interface of the die with direct memory access. Intel processors have a distinct architectural advantage here since their monolithic dies with interleaved memory controllers feed each core with nearly equal memory access. Platform costs of the Threadripper processors are roughly on par with Intel's X299 platform. Motherboards that can comfortably run WX chips are priced north of $300, and you need at least four matched memory modules. At $1,300, the Threadripper 2970WX could be highly competitive to similarly priced Intel options, such as 14-core "Skylake-X," provided your machine is used for intense rendering workloads. It won't speed up your Premiere Pro video mastering workloads significantly. Neither will your database server or machine learning tasks get much faster. Virtual machines also won't see significant benefits because all these tasks make use of memory. So Threadripper 2970WX is the solution for one small niche case: rendering. If you are in the market for a rendering farm, then building it using Threadripper WX could be a huge money saver because comparable Intel CPUs are much more expensive. If you are looking to satisfy a wider range of workloads, then the 16-core Threadripper 2950X is almost always a better choice. Should you still need more performance, get ready to either shell out $1,800 for the Core i9-7980XE or explore Xeon-W options such as Intel's elusive 28-core "unlocked" processor, which will be light years away from the word cheap.
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