AMD launches Ryzen 7040U series processor with Zen 4c cores

AMD’s innovative Phoenix 2 chip, embracing a Zen 4 and Zen 4c hybrid architecture, was initially deployed in the handheld gaming market through the Ryzen Z1 processor. AMD, however, did not confine this chip’s application to that niche alone. They have now propelled it into the mobile computing sphere, exemplified by the recent launch of the Ryzen 5 7545U and Ryzen 3 7440U processors—both exemplars of the hybrid architecture incorporating Zen 4c cores.

The Phoenix 2 chip is substantially more compact than the original Phoenix version. While Phoenix boasts eight Zen 4 cores with a graphical unit composed of 12 RDNA 3 architecture Compute Units (CUs) and includes a Ryzen AI unit, the Phoenix 2 is configured with 2 Zen 4 and 4 Zen 4c cores, with only four groups of CUs and devoid of the Ryzen AI component.

The Ryzen 5 7545U features two Zen 4 and four Zen 4c cores, totaling six cores and twelve threads, accompanied by a 16MB L3 cache and operates at a base frequency of 3.2GHz that can boost up to 4.9GHz. The Ryzen 3 7440U comprises one Zen 4 and three Zen 4c cores, amounting to four cores and eight threads, with an 8MB L3 cache, and a base frequency of 3.0GHz scaling up to 4.7GHz. Both processors are equipped with the Radeon 740M integrated graphics, which include four groups of RDNA 3 architecture CUs, and both possess a Thermal Design Power (TDP) ranging from 15 to 30 watts.

Zen 4c cores

These processors are built on TSMC’s 5nm process technology. A single Zen 4 core occupies an area of 3.84mm², whereas the more diminutive Zen 4c core occupies just 2.48mm², which denotes a substantial reduction in core surface area by 35.4%, signaling a remarkably more compact design. Both feature a 1MB L2 cache, suggesting the L2 SRAM unit occupies a consistent area across both core types. AMD has achieved a reduction in the L2 cache’s footprint by condensing the control logic circuitry, which leads to a dramatic reduction in the core area by 44.1% for regions excluding the L2 cache and related circuitry, nearly halving the area of the front-end and execution domains. The Floating Point Unit (FPU) has not been reduced as significantly, likely a deliberate choice to accommodate thermal considerations, as the FPU is typically the hottest component of the core. Additionally, a more compact layout of the core’s SRAM units has been realized, trimming the core area by 32.6%.

In contrast to Intel’s approach of coupling P-Cores with E-Cores based on divergent architectures, Zen 4 and Zen 4c are fundamentally identical, sharing the same Instruction Set Architecture (ISA) and Instructions Per Cycle (IPC). However, the compact design of Zen 4c dictates a lower operational frequency compared to the standard Zen 4, a necessary compromise to manage heat dissipation. The Zen 4 cores in the Ryzen Z1 can reach frequencies up to 4.9GHz, whereas the Zen 4c cores max out at 3.5GHz.

AMD conducted a performance comparison between the six-core Zen 4 Ryzen 5 7540U and the Zen 4 and Zen 4c hybrid Ryzen 5 7545U at various power consumptions. Below the 15W threshold, the Ryzen 5 7545U demonstrates superior performance over the Ryzen 5 7540U. The divergence point in performance between the two types of cores is around 20W; beyond this power level, the Zen 4 begins to outpace the Zen 4c. However, it must be noted that when compared to the performance disparity between Intel’s P-Cores and E-Cores, the difference between Zen 4 and Zen 4c is quite nominal.