AMD’s first hybrid chips feature Zen 4 and smaller Zen 4c cores

Most of the AMD Ryzen 7040 “Phoenix” chips that have shipped to date feature a combination of Zen 4 CPU cores and RDNA 3 graphics. But the company has quietly begun shipping processors that feature “Phoenix 2” architecture with a mix of Zen 4 and smaller Zen 4c CPU cores.

While AMD hasn’t officially said much of anything about the new architecture, details emerging out of China confirm that some of the company’s cheaper processors feature this sort of hybrid architecture, representing the first time AMD has mixed two different types of CPU cores on the same chip.

That’s something ARM has been doing for over a decade, with its big.LITTLE architecture that pairs high-performance and energy-efficient CPU cores on the same package. And Intel widely adopted the use of Performance and Efficiency cores beginning with its 12th-gen Core processors.

Details about the new Zen 4c cores have been leaking for months, but now HXL (@9550pro) has shared pictures from Chinese social media that show the die shot, confirming that Zen 4c cores take up less space and have a few other modifications that will likely lead to lower performance in some situations.

According to VideoCardz, AMD’s first chips to feature the new hybrid architecture include the Ryzen 3 7440U (with 2 Zen 4 + 2 Zen 4c cores), the Ryzen 5 7540U (with 2 Zen 4 + 4 Zen 4c cores), and the Ryzen Z1 (the entry-level gaming chip that will be a cheaper, lower-performance alternative to the Z1 Extreme used in the top-of-the-line Asus ROG Ally and Lenovo Legion Go).

AMD’s hybrid chips seem to be a little different than Intel’s. While Intel’s Efficiency cores, for example, do not support hyperthreading and are based on different architecture than its Performance cores, AMD’s Zen 4c cores seem to be use the same technologies as its Zen 4 cores… just less of it.

For example, Zen 4c cores support hyperthreading, so each CPU core supports two threads. Intel’s Efficiency cores are single-threaded only.

But Zen 4c chips tend to be paired with fewer graphics compute units, and some models also appear to have less L2 cache memory

Based on the chip model numbers and what we’ve now learned about the new processors, it seems like a safe bet that the new Phoenix 2 processors will deliver lower performance than their original Phoenix counterparts like the Ryzen 3, and a Chinese report analyzing performance of the AMZ Z1 processor seems to confirm that.

Cool, matches up with Semianalysis’ more detailed overview/speculation from June. I made a mashup of the two sources to see how they changed, the scaling matches perfectly. pic.twitter.com/ifif3M0dZg

— HyenaDae (@dae_hyena) September 10, 2023