AMD Ryzen Threadripper 3960X Review

👤by David Mitchelson Comments 📅25-11-19

Third Generation Threadripper a middle-ground between 3rd Gen Ryzen and EPYC server-class chips: while still based on Zen 2 microarchitecture with the 8-core 7nm Core Complex Die as a key component, it incorporates a revised 14nm IO Die that reflects the requirements of the niche HEDT market. The range is launching with the 24-core Threadripper 3960X and 32-Core Threadripper 3970X that have the following unifying aspects to their design.


On a physical level, these CPUs incorporates four CCDs and an IOD onto a single substrate, offering up to 32-cores with Simultaneous Multithreading support. Thats a substantial change from Zen+, where each die on the CPU was in effect a fully working CPU that was working in tandem with up to three others to make up a processor that supported as many as 32 cores (or as few as  8).

The specifications show the same increase in base and boost clocks that 3rd Generation Ryzen enjoyed, thanks in part to the 7nm lithography and new design. Both SKUs have high base and boost operating frequencies compared to their 2nd Gen counterparts, now reaching up to 4.5GHz, but multi-core load performance will be dictated by the boosting algorithm and cooling solution.

Augmenting the higher clocks is an expected improvement in IPC, which would mean that all-round performance compared to the last-generation 2990WRX will be higher. AMD estimate an approx. 30% improvement in 3970X vs 2990WX based on these parameters.

IPC improvements are in part due to the huge Cache increase in Zen 2. The amount of L3 Cache to has doubled to 128GB (compared to 64GB on the 32-core 2990 WRX), increasing hit rate and reducing how often slower memory accesses are required.

At an architectural level, substantial changes have been made in CPU front and back-end which may particularly impact workhorse compute tasks often expected of a pseudo-workstation HEDT platform. As we oulined in our Ryzen launch reviews, significant changes have been made to the L1 and L2 cache structures alongside the huge increase to the L3 cache size.

As with virtually every other Ryzen CPU these Threadripper are overclockable. A couple of words caution however: Ryzen CPUs already appear to be operating with little practical headway for overclocking (the Boosting algorithm generally performing an acceptable roll in reaching the CPUs potential), and as a 280W TDP part cooling for even modest overclocks will likely need to be exceptional.

Memory and Infinity Fabric overclocking may be good stand-ins for enthusiast overclockers looking to make the most of their benchmarking software. As with 3rd Gen Ryzen, Threadripper motherboards should offer infinity fabric frequency support decoupled from memory frequency in an optional 2:1 ratio.


For the first time in three years a new AMD CPU in being introduced alongside a new socket - sTRX4. AMD have stated that this socket specification is not backwards compatible with sTR4/X399 motherboards, and have explained that new features - particularly PCIe 4.0 signaling and platform scalability - made cross-support with the previous generation impractical. Those who recently bought X399 motherboards hoping for forwards compatibility will be kicking themselves.

The rather novel slot-loading CPU installation makes a return from the previous HEDT range, and that lack of thousands of pins on the underside will mean it’s quite durable all things considered. Early adopter issues with that socket design should now be well and truly solved.

Users will not be lumbered with the spotty cooler support enjoyed by 1st Gen Threadripper when it launched a few years ago. An identical CPU footprint and cooler mounting point layout means that older sTR4 coolers are fully compatible, but need to be rated at up to 280W. Coolers certified for the top-end 2nd Generation Threadrippers should be acceptable for the 3rd Generation.


Memory and I/O signalling is routed through the IOD, which now needs to handle quad-channel memory at DDR4-3200MHz, up from DDR4-2933MHz on 2nd Generation Threadripper. Memory is overclockable, but the more robust Zen 2 memory controller (in addition to the decoupled infinity fabric clock) should mean higher achievable frequencies. Quite the boon for more memory-intensive applications common to HEDT workloads.

While memory improvements could be viewed as only incremental, PCIe 4.0 is a major advanced. Still and AMD exclusive technology for the time being, it offers double the bandwidth compared to PCIe 3.0 for faster storage and graphics bandwidth capabilities on the HEDT platform.

The number of PCIe lanes available has also increased, from 64 to 72. More of these lanes are dedicated to Chipset communication (the GMI link in AMD parlance) than previously, boosting bandwidth 4x over the previous generation, and the chipset will offer downstream PCIe 4.0 depending on system configuration.

Motherboard loadouts will determine the use of the PCIe 4.0 lanes. By default 48 are apportioned to expansion slots and 8 to the chipset, but beyond that it could be utilised by NVMe, SATA or general PCIe peripheral use.

Last by not least, 3rd Gen. Threadripper supports up to 1TB of DDR4 RAM, 256GB per channel. This will require eight fully populated DIMM slots but not all TRX40 motherboards will necessarily be fitted with this many.

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