AMD Threadripper 3990x is right here: 64 cores, 128 threads, $3,990

Enlarge /. It looks like the Empire is cooling this CPU down by freezing it in carbonite.

On Friday, AMD introduced its latest Monster CPU – the 64-core 3990x thread ripper with 128 threads. The 3990x is not the first publicly available x86-64 CPU with 128 threads. This award applies to AMD's Epyc 7742, 7702 and 7702P in three directions. But the 3990X is the first "desktop" CPU that offers so many threads – and puts a strain on the ecosystem.

Cost per thread

Despite the groundbreaking specifications for the TR3990x, AMD is sticking to the pricing strategy it has followed for years: choose the CPU that meets your needs and pay a reasonable, roughly linearly scaled price. If you want thread ripper cores, you will pay around $ 30 each, regardless of whether you are looking for smaller or larger parts.

This is in sharp contrast to Intel's pricing strategies, which for years have aimed to "choose the CPU you can afford" rather than "choose the CPU that suits your needs". The best example of this strategy is Intel's premier Intel Xeon Platinum series, which is literally priceless – they're not commercially available – but is reasonably priced around ten times as much per thread as the closest competing Epyc parts.

However, we have seen a major change in Intel's HEDT (High End DeskTop) CPU pricing strategy since the introduction of 3rd generation Threadripper. Team Blue halved the price of its flagship HEDT in a single year. As a result, the cost of the top core i9 part per thread matched the cost of the competing thread ripper parts – and was even slightly cheaper than this.

Back to Team Red: The 64-core Threadripper is a little cheaper than the 64-core Epyc 7702P with a socket – but not enough to write home with. As a result, the decision to build a system around the TR3990x or 7702P remains more and more in search of a build that fits the workflow, rather than at a cost that fits in your wallet.

Why (or why not) thread ripper?

Threadripper and Epyc have more in common than not. Both families offer an incredible number of cores, support for ECC-RAM and a relatively high number of PCIe 4.0 lanes. Given the cost per thread of distance from one another, a cautious system builder can take care of the remaining differences between architectures than total costs.

3rd generation Threadripper can reasonably be seen as 3rd generation Epyc with higher clock speeds, but fewer PCIe 4.0 lanes, fewer memory channels and support for less total memory. It's an optimal setup for jobs like 3D rendering, which typically experience bottlenecks in raw multi-threaded CPU performance – but not so much for jobs that have memory throughput bottlenecks or require massive in-memory datasets.

As reported in Aneltech's excellent test report on the 3990x thread ripper, the latest thread ripper also reaches the limits of what the industry actually wants to call "desktop". Windows 10 Professional throttles quite a lot when presented with the 128 cores of TR3990x and organizes them as two CPU groups – which in some places is incorrectly referred to as multiple "sockets".

Windows 10 Pro's lack of support for so many threads on a single socket isn't just a weird-looking quirk. On Windows 10 Pro, some benchmarks run twice as fast when hyperthreading is disabled so that the operating system does not adjust them incorrectly to group them into separate "sockets", which are then treated according to the NUMA rules. It can help prevent threads from crossing real physical processor limits, but it can be debilitating if the actual limit doesn't exist at all.

Ultimately, this means that Windows 10 Pro is not suitable for Threadripper 3990x at all. If you're building a 3990x system, you'll need to upgrade from Pro to Workstation for around $ 120 or plan to pay $ 84 a year for a Windows 10 Enterprise subscription system. Windows 10 Workstation and Enterprise both support the 128 threads of the TR3990x without organizing them in nonexistent sockets and without the associated performance degradation.

None of this is a problem for Linux users. Although the performance-optimized Clear Linux distribution from Intel surpasses the normal "Daily Driver" distributions, this is no longer the case with the Threadripper 3990x than with a Ryzen 5 3400G with a low quad-core value. If you want to run a 3900x on bone on Ubuntu, you can do it and you'll be fine.

Conclusions

Threadripper 3990x, like the 3970x that was there before, is a very specialized beast. If you need the enormous number of threads that each CPU brings to bear and don't need more than 256 GB of RAM, they are a breeze. However, it is a mistake to consider them optimal CPUs for games or for any workload that does not use their massive parallelism effectively. While they are no slower than the much cheaper Ryzen 9 3950X for single-threaded or slightly multi-threaded tasks, they are no faster for these tasks – and they are significantly less efficient.

The good

• 128 threads – oh my god! No one has yet built a 128-thread HEDT CPU.
• The cost per thread is not significantly higher than other Threadripper HEDT parts (or competing Intel HEDT parts).
• Already available in retail OEM systems – including OEM Linux workstations.
• Compiles a modern Linux kernel in 24 seconds.

The bad

• No instructions for AVX-512 / Deep Learning Boost x86 – AVX-512 workloads run faster on much smaller, cheaper Intel CPUs.
• 128 topics – oh my god! Some operating systems and applications are not yet able to cope with this scaling.
• Even with the latest RAM, 3990x only supports 2 GB RAM per CPU thread.

The ugly

• Share office space with a thread ripper system in a South Carolina summer