The existence of AMD Phoenix mobile APUs with hybrid architecture was recently spotted as a successor to the Ryzen 7040 series that debuted at CES 2023. The previously announced Ryzen 7040 APUs combine Zen 4 CPU cores with RDNA3 graphics architecture in an integrated package, making for some potent mobile chips. These new hybrid Phoenix APUs are expected to shake up the formula a bit by utilizing two types of CPU cores.
The hybrid Phoenix APUs are said to use a mix of “big” Zen 4 cores for heavy lifting and “small” Zen 4C cores to handle background tasks. The idea sounds similar to Intel’s asymmetric approach, which has been used since Lakefield, but a new leak shows how much AMD mirrors its rival.
#AMD in the Phoenix1 Processor Programming Reference (PPR) uses the same terminology for the big and small cores as #Intel https://t.co/4gWXpC8Bkg https://t.co/2RbTR2DRWV pic.twitter.com/8JmBB0RIzt
— InstLatX64 (@InstLatX64) March 24, 2023 The new information comes from Twitter leaker InstLatX64, who reveals that AMD goes as far as adopting Intel’s terminology to distinguish them: performance cores and efficiency cores. Whether this nomenclature will ultimately be used in marketing or other consumer-oriented materials is uncertain. The leaked document is part of a programming guide intended for developers, so AMD may still be using its own nicknames once these products are officially announced.
We don’t yet know exactly how a Zen 4C core differs from its full-fledged Zen 4 counterpart. Aside from these mobile chips, we know that the Zen4C architecture will also find its way into AMD’s Bergamo data center chips. Bergamo recommends deploying up to 128 Zen 4C cores (256 threads) in a single socket for cloud-native applications that prefer high availability of cores over individually powerful cores. These qualities make Zen 4C similarly suited as fallback cores for a laptop’s background tasks, where lower power consumption translates directly to improved battery life.
InstLatX64 concludes that Zen 4C and Zen 4 may be more similar than Intel’s performance and efficiency cores. “It appears AMD is sacrificing half L3 and some frequency for the half-size Zen4c,” the tipster explained in a follow-up tweet. InstLatX64 also notes that a Zen 4 core is roughly twice the size of a Zen 4C core, while Intel’s P-core is roughly 3.5 times larger than its E-core.
AMD’s strategy of keeping two broadly similar cores could prove beneficial. Intel’s Efficiency core is Gracemont-based and lacks some features found in Golden Cove-derived performance cores. Most notably, AVX-512 is disabled in the company’s 12th and 13th generation desktop processors, despite physical support in the P-cores (AVX-512 is enabled in Intel’s Xeon Scalable CPUs with all P-cores) . AMD’s presumed demarcation would leave fewer discrepancies and potentially ease development requirements.
AMD’s existing mobile Ryzen processors have already proven that they can deliver strong efficiency gains over Intel’s hybrid CPUs. We’re excited to see how these hybrid Phoenix APUs perform in practice once we get our hands on them. The hybrid Phoenix APUs are expected to feature two Zen 4 cores and four Zen 4C cores with two RDNA3 WGPs on the top end. So we expect to find laptops with these chips in the “thin and light” range, rather than the high end. Gaming”-oriented brutes.
