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The reasons why AMD hasn’t released a Ryzen 9 with 3D V-Cache

The expectation was maximum from the gamer’s point of view to know and know all the CPUs that AMD was going to include in its new range of desktop CPUs. But this presentation yesterday was limited to a single model that left everyone cold, where the questions were thrown behind the scenes. Why are Lisa Su’s going to compete with a single Ryzen 7 5800X3D model against the entire Intel Core 12 lineup?

5800X3D Design, Costs, and Performance

AMD Ryzen 7 5800X3D specifications

Innovating is not easy, much less if we talk about vertical stacking. Intel has an advantage in this regard and although it does not have a single product on the desktop with its Foveros technology, AMD and TSMC are curiously ahead and are at the forefront with 3D V-Cache. The one chosen as we saw yesterday is the current Ryzen 7 5800X, which sees its 32 MB of L3 expand to nothing less than 96 MB using a smaller vertical silicon.

To be specific, we are talking about the fact that the die Core of the 5800X that it shares with all models from the 5 series measures 82 mm2 of area. AMD has had to reduce that area in its vertical Cache silicon to only 36 mm2 manufactured in the same 7 nm as the so-called CCD, so the option was to connect cache with cache through TSV and Micro Bumps 3D. What happens to the rest of the area that is at another physical height? It is filled with silicon in what has been called “Thermal Spaces” so that it is a flat surface in contact with the IHS.

Lower frequency and same TDP

AMD-Ryzen-7-5800X3D

Apart from the total L3 cache that goes from the aforementioned 32 MB to 96 MB for the vertical 64 MB stack, the only difference between versions is that the frequency in this 5800X3D has dropped 200 MHz to 4.5 GHz. So to sum up, a single 3D V-Cache gaming CPU, with more L3, lower clock rate versus the entire Intel rollout, why?

Here comes the interesting thing. There are 3 reasons explained by AMD itself for this brief launch. The first is that we want to verify the impact of the V-Cache on sales, since including the vertical L3 implies an additional cost in chip and packaging together, so in the face of the shortage of existing chips, a CPU with a single CCD is more optimal in order to have units.

Second, a single chiplet with V-Cache is easier to optimize than dealing with two directly, as it is a cutting-edge technology at TSMC. Finally, AMD talked about power and consumption. It is the case that the extra cache adds a few watts to the actual CPU consumption, even when the CPU is idle.

Therefore, given the increase in IPC and gaming performance obtained with this improvement, it was considered to reduce the frequency to maintain temperatures and consumption throughout the voltage range and above all, allow some overclocking manual or with PBO.

Also, this Ryzen 7 5800X3D would be faster than the i9-12900K and only slower than the KS version of it and for very little, so really AMD would be competing for the crown of gaming performance with a cheaper contender than Intel, although with fewer total cores. It is according to Lisa Su’s, a 15% faster than 5900X, so its price will be the key factor to position it as attractive or not.

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