AMD Stacked 3D V-Cache Could Be Headed To Gaming GPUs After Zen 3 Ryzen Refresh
AMD's Zen 2 and Zen 3 processor cores stack up pretty well against Intel's finest, largely thanks to the use of a secret weapon: massive last-level caches. The company's Radeon arm pulled the same trick—calling it "Infinity Cache"—to allow its recent Radeons to compete with Mean Green on performance despite coming strapped with relatively-puny memory interfaces.
Soon, AMD's doubling down on that play with refreshed Ryzen CPUs bearing 3D stacked cache, known to date as "3D V-Cache." The concept is simple: AMD is literally piling on extra last-level cache using vertically stacked dice. The upcoming "Zen 3+" refresh will be fundamentally the same CPUs as in the extant Ryzen 5000 series, just with each 8-core Core Complex Die (CCD) bearing an extra 64MB of cache on top, for 96MB on single-CCD parts, and a whopping 192 MB of L3 cache on dual-CCD parts. The closely-related EPYC Milan-X CPUs are getting the same treatment, too, and their 8 CCDs end up stacking up a total of 804MB of L3 cache.
The company hasn't said a word about 3D V-cache on graphics products, but AMD's just filed a trademark request with the United States Patent and Trademark Office for the specific phrase "3D V-Cache." That isn't surprising in and of itself, but buried in the trademark filing we can find the list of types of products for which the trademark will apply. There's the expected CPUs and SoCs, as well as DRAM and its controllers, but mentioned numerous times in the filing are AMD's other big product: GPUs.
Does this automatically mean that we're going to be seeing 3D V-cache appear on discrete graphics products? Well, no, not necessarily. Even though the filing specifically mentions "graphics cards" in addition to numerous instances of "GPU," AMD could simply be filing the trademark now in case it decides to do such a thing in the future.
With that said, the latest rumors indicate that AMD's next-generation flagship Radeon parts will have an absolutely enormous amount of "Infinity Cache"—up to 512 MB, if the leakers are legit. Adding on that much cache to a monolithic part would make the die extremely large, while using a stacked V-cache die could help keep the maximum die size down while still reaping the benefits of a large cache—benefits we observed ourselves back when the RX 6800XT launched.
It makes sense, but will it come to pass? All we can do is wait and see.