Review: Ryzen 7 5800X3D is an interesting tech demo that’s hard to recommend

AMD's Ryzen 7 5800X3D.
Enlarge / AMD’s Ryzen 7 5800X3D.

Andrew Cunningham

AMD’s AM4 socket had a long and successful run on the desktop, ushering in the Ryzen line of processors and helping AMD compete and outperform Intel’s chips for the first time since the mid-2000s.

The days of the aging socket come to an end later this year when the Ryzen 7000 series chips are released, but AMD is shipping it with a latest high-performance processor: the Ryzen 7 5800X3D, which launches April 20 for $449. .

AMD is using a unique packaging technology called “3D V-Cache” to triple the amount of L3 cache on the processor, from 32MB for the standard Ryzen 5800X to 96MB. This new technology feels like an experiment in some ways. Unlike other Ryzen CPUs, the 5800X3D doesn’t offer any overclocking or power consumption controls, and its clock speeds are a bit lower than the standard 5800X. But AMD says the extra cache helps the 5800X3D outpace Intel’s fastest processors when it comes to gaming.

We ran tests on the 5800X3D to find its strengths and weaknesses and to get an idea of ​​when you’ll notice the impact of the extra cache. It is undoubtedly a interesting processor, but its extremely specific price and performance advantages will limit it to a niche niche.

V-Cache 3D, in a nutshell

A visualization of AMD's 3D V-Cache.
Enlarge / A visualization of AMD’s 3D V-Cache.

AMD

Architecturally, nothing about the Zen 3 cores that power the 5800X3D has changed from the vanilla 5800X. We’re still talking about an 8-core, 16-thread complex (CCD) chip built on TSMC’s 7nm process, with its 32MB of L3 cache intact. Just as Apple built interconnect support into the M1 Max to support the M1 Ultra, AMD created Zen 3 to support 3D V-Cache whenever it was ready to ship. .

The main change is that AMD and TSMC reduced the physical height of the CCD chip so that a CPU package with 3D V-Cache need not be physically taller than a CPU package without it. This adjustment preserves compatibility with existing CPU coolers.

The additional 64MB of L3 cache, also built on TSMC’s 7nm process, is physically stacked on top of the Zen 3 CCD and connected with a direct copper-to-copper link. The result is something the system considers a large pool of L3 cache that can all be treated equally – the 64 MB of stacked cache is not L4 cache, and the 32 MB of L3 cache built into the CCD n don’t have any. performance advantage over cache stacked above.

The copper-to-copper bond is used to fuse the CCD and the additional cache.
Enlarge / The copper-to-copper bond is used to fuse the CCD and the additional cache.

AMD

A side effect of this packaging technology is that the 5800X3D runs at a noticeably slower clock speed than the 5800X, and AMD officially does not allow any overclocking or power tuning when using the 5800X3D. AMD is pushing the 5800X3D primarily as a gaming processor, and that’s because games more consistently benefit from having a larger cache pool to play with. For workloads that care less about cache and more about clock speed, as we’ll see when we start benchmarking, the 5800X3D can be Slow down than the regular 5800X, which AMD freely admits.

AMD’s 8-core Zen 3 processors Public price Clocks (Base/Boost) L3 cache PDT PCIe support
Ryzen 7 5700G $280-300 3.8/4.6 16 MB 65W 3.0
Ryzen 7 5700X $299 3.4/4.6 32 MB 65W 4.0
Ryzen 7 5800X $340-360 3.8/4.7 32 MB 105W 4.0
Ryzen 7 5800X3D $449 3.4/4.5 96 MB 105W 4.0

AMD has been playing coy about whether we can expect future Zen 3 processors with 3D V-Cache enabled, but reading between the lines, it seems unlikely. 3D V-Cache will be one of the tools in AMD’s toolbox when it comes to improving the performance of Zen 4 platforms and early Socket AM5 platforms, as well as a TSMC process 5nm, DDR5 support and other architectural improvements, but I don’t understand the feeling that the 5800X3D will be followed by an extended line of Zen 3-based X3D chips.

AMD says motherboards will need a BIOS update to see and use the extra 64MB of cache. Look for AGESA version 1.2.0.6b or higher in the release notes. Motherboards that support other Ryzen 5000 processors will work with the 5800X3D, but they won’t be able to access the extra cache, which defeats the purpose of spending more money on the processor first place.

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