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

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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 with and outperform Intel’s chips for the first time since the mid-2000s.

The days of the aging socket will come to an end later this year when the Ryzen 7000-series chips launch, but AMD is sending them off with one final high-performance processor: the Ryzen 7 5800X3D, due April 20 for $449. dollars hit the market.

AMD uses 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 a whopping 96MB. This new technology feels like an experiment in a way. Unlike other Ryzen CPUs, the 5800X3D doesn’t offer overclocking or power consumption controls, and its clock speeds are a bit low lower than the standard 5800X. But AMD says the extra cache will allow the 5800X3D to overtake Intel’s fastest CPUs when it comes to gaming.

We ran some tests on the 5800X3D to find out its strengths and weaknesses and to get a sense of when you’ll start to notice the effects of the extra cache. This is undoubtedly one Interesting processor, but its pricing and highly specific performance benefits will limit it to a niche within the niche.

3D V-Cache in a nutshell

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

AMD

Architecturally, the Zen 3 cores that power the 5800X3D have not changed compared to the vanilla 5800X. We’re still talking about an 8-core, 16-thread Core Complex Die (CCD) based on TSMC’s 7nm process, with its 32MB L3 cache intact. Just as Apple built interconnect support into the M1 Max to support the M1 Ultra, AMD designed Zen 3 to support 3D V-Cache technology whenever it was ready to ship.

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

The 64MB additional L3 cache, also based on TSMC’s 7nm process, is physically stacked on the Zen 3 CCD and connected with direct copper-to-copper bonding. The result is what the system sees as a large pool of L3 cache, all of which can be treated the same – the 64MB of stacked cache is not L4 cache, and the 32MB of CCD onboard L3 cache is not Performance advantage over the cache stacked on top.

Copper-to-copper bonding is used to fuse the CCD and additional cache together.
Enlarge / Copper-to-copper bonding is used to fuse the CCD and additional cache together.

AMD

A side benefit of this packaging technology is that the 5800X3D runs at a noticeably slower clock speed than the 5800X, and AMD does not officially allow overclocking or performance tuning when using the 5800X3D. AMD is pushing the 5800X3D primarily as a gaming processor, and that’s because games will 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 may be right up your alley Slower than the regular 5800X, which AMD openly admits.

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

AMD has played coyly about whether we could expect future Zen 3 CPUs 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 boosting performance for Zen 4 and early socket AM5 platforms – along with a 5nm TSMC process, DDR5 support and others architectural improvements – but I don’t get the feeling that the 5800X3D will be followed by an expanded range of Zen 3-based X3D chips.

AMD says motherboards need a BIOS update to see and take advantage of the additional 64MB of cache – look for AGESA version 1.2.0.6b or later in the release notes. Motherboards that support other Ryzen 5000 CPUs will work with the 5800X3D but won’t be able to access the extra cache, defeating the purpose of spending more money on the CPU in the first place.


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