With the arrival of AMD’s Ryzen 7 5800X3D processor, the consumer market has a CPU with a lot of L3 cache memory. Because the latency of cache memory is significantly lower than that of working memory, the chip has the potential to perform much better in games. AMD therefore presents the 5800X3D as the ultimate processor for gaming. In our extensive review you can read all about the performance of this new Ryzen processor in a large number of ran tests and benchmarks.
More cache for performance gain, not a new concept
According to AMD, the workloads involved in gaming are very random and largely unpredictable when it comes to cache. If the required data is not available in the cache memory, the working memory must be accessed. Because the speed and especially the latency of working memory is a lot less favorable in relation to cache, the (gaming) performance in such a case depends very much on the speed and latency of your ram.
The technology behind 3D V-cache is new, but the overall concept of adding more cache for performance gain is not. The enterprise market has several examples of this, while the Broadwell generation, with the Intel Core i7 5775c as flagship, is a well-known example among consumer processors. This processor from 2015 got no less than 128MB of cache memory added on a separate chip, even more than the new Ryzen CPU. The big difference is that this extra memory was used on Broadwell processors as an entirely new L4 cache level, while on the 5800X3D it is an extension of the L3 cache. Moreover, this L4 cache on Broadwell chips can also be used for the integrated GPU, which is of course absent on the 5800X3D. In the presentation about the 5800X3D, AMD did indicate that it sees possibilities to use 3D V-cache for an igpu in the future.
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Ryzen 7 5800X3D: No need for fast RAM anymore?
In this article we look at the influence of 3D V-cache in combination with the speed of the working memory. Because the 5800X3D has so much more cache memory than other Ryzen 7 processors, in theory less need to be made of the working memory. We have extensively tested for this article whether the 5800X3D with its larger amount of cache is actually less dependent on the speed of the working memory.
| Memory Speed | max. throughput per module | Memory Timings Used | True latency module |
|---|---|---|---|
| DDR4-2666 | 21,333 MB / s | CL16-16-16-16-38 | 12ns |
| DDR4-3200 | 25,600 MB / s | 10ns | |
| DDR4-3600 | 28,800 MB / s | 8,89ns |
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For this comparison, we run a selection of our regular tests with both the Ryzen 7 5800X3D and the regular 5800X combined with DDR4-3200, the maximum officially supported memory speed. In addition, we also test these two processors with DDR4-2666 and DDR4-3600, in order to include a slower and a faster memory option in the comparison. To reinforce the disadvantage of slow working memory and the advantage of fast working memory, we have kept the memory timings of these three speeds the same. In this way we create clear differences between the three throughput speeds and the associated latencies of the working memory.
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