AMD formally launches Ryzen 5 7545U and Ryzen 3 7440U featuring efficient Zen4c cores

AMD details Zen4c cores in consumer Ryzen 7040U series

The company is providing new details on their hybrid implementation of Zen4 architecture.

It is no secret that the Ryzen 7040U series indeed incorporates both Zen4 and Zen4c cores. This information has been available since the series was announced, as AMD confirmed the use of two distinct dies for this lineup. Leakers have contributed additional details by suggesting that certain parts within the series will include smaller Zen4c cores borrowed from the data-center EPYC series.

Today, AMD is officially introducing two parts in the 7040U series, namely the Ryzen 5 7545U and Ryzen 3 7440U, both featuring a combination of these core types. This marks the first instance of a heterogeneous CPU architecture, akin to Intel’s hybrid design of P-Cores and E-Cores. However, AMD asserts that its approach offers superior performance for several reasons.

AMD Ryzen 7040U series, Source: AMD

The Zen4c cores share the same instruction set as their non-C counterparts, provide identical IPC, and support SMT (multi-threading). Notably, they don’t require any OS scheduler activation, and these cores exhibit comparable efficiency to their larger counterparts. Furthermore, there’s no need for the operating system or any software to determine core utilization for gaming.

Zen4c cores will be found in at least three products: Ryzen 7 7545U, Ryzen 3 7440U, and Ryzen Z1 non-Extreme. These chips are based on the Phoenix2 chip, sometimes referred to as “Little Phoenix” by hardware enthusiasts. It features a smaller die compared to the “Big Phoenix,” with a different core and GPU subsystem layout (137mm2 vs. 178mm2).

Notably, the Phoenix2 lacks the XDNA core for Ryzen AI acceleration, and its maximum core configuration includes 2x Zen4 and 4x Zen4c cores. However, the graphics are notably downsized to just 4 RDNA3 units (marketed as Radeon 740M), which is three times fewer than the Radeon 780M.

So, what’s the rationale behind employing Zen4c cores in these CPUs? Zen4c is a smaller and denser core previously exclusive to the EPYC Bergamo series. AMD managed to reduce the core size by 35% compared to full Zen4 cores, albeit at the cost of slightly lower clock speeds due to decreased high-performance libraries.

AMD Zen4 vs Zen4c, Source: AMD

Nonetheless, AMD claims that this architecture should deliver energy efficiency when comparing both cores on a clock-to-clock basis. The smaller Zen4 cores, with similar IPC, are expected to be more power-efficient at lower TDPs, something that laptop designs can leverage.

AMD Zen4 vs Zen4c, Source: AMD

In today’s launch, AMD is offering two components: the Ryzen 5 7545U, which shares specifications with the 7540U but replaces the 6 Zen4 cores with two Zen4 and a cluster of four Zen4c cores. The Ryzen 3 7440U is even more intriguing, featuring 1 Zen4 core and three Zen4c cores, akin to Intel’s Lakefield with its 1+4 core arrangement.

It’s essential to note that the Zen4c cores are distinct from Zen4, despite AMD’s portrayal. According to Anandtech, AMD should disclose clock speeds for these cores separately, but that’s not the case in the official specifications.