AMD’s Zen 4c Core Makes Its Way Into Ryzen 5 7545U & Ryzen 3 7440U Processors
AMD’s Zen 4c Core Makes Its Way Into Ryzen 5 7545U & Ryzen 3 7440U Processors
After making its entrance through “Bergamo” and “Siena” EPYC CPUs, and later AMD Z1 processor, the Zen 4c is now officially entering the laptop segment: AMD is announcing two new models featuring the company’s take on hybrid architecture, which packs a mixture of full-size Zen 4 core and downsized Zen 4c core into a single package.
So what’s the difference between Zen 4 and Zen 4c cores? Essentially, the company says the Zen 4c is just an size-optimized version of the Zen 4 core, focusing on die size and efficiency fronts as opposed to the more performance-oriented nature of the standard core design (with no changes made on the instruction set). This means that both types of cores are the exact same to the operating system, meaning there’s no need for a hardware-based scheduler (like Intel’s Thread Director) to allocate workloads to the corresponding cores.
Today Team Red is launching two SKUs with such designs – the Ryzen 5 7545U (2C+4c, 12 threads) and the Ryzen 3 7440U (2C+2c, 8 threads). AMD noted that the 7545U will directly replace the previously-announced 7540U (with 6 full-size Zen 4 cores), citing that no laptops has used this chip on the market, thus prompting this change.
In terms of performance implications, first party data indicates that the Zen 4c-infused Ryzen 5 7545U performs up to 10% better over 7540U in scenarios using 15W or less, and as the power scales up, both chips are about the same at 20W. In higher power scenarios (28W), the 7540U overtakes by around 5% in Cinebench R23 multi-core test. In a sense, the 7545U presents an improvement given that these chips will feature in low-power designs that uses 15W, rather than performance-oriented laptops using 28W of power.
Another point AMD brought out is that Zen 4 boosts higher than Zen 4c cores – but that shouldn’t make any difference in terms of how operating systems sees the cores. Traditionally, CPUs always have one or two preferred cores (as with the nature of silicon lottery), so there are no code changes needed on OS’s part to utilize this new core layout. The company cited that 7545U’s 2C+4c layout presents the “ideal combination of performance and efficiency”.
Finally, the company stressed that Zen 4c is *not* like Intel’s E-cores. The E-cores are architecturally different than P-cores, with reduced instruction sets and no multithreading support, necessitating a hardware-based scheduler like Thread Director to make full use of the core configuration. On the contrary, AMD’s Zen 4 + Zen 4c design is virtually seamless as no changes are needed on the software side of things to make use of the extra bit of efficiency (in both power and die area) it offers.
Pokdepinion: I reckon this should make low-power segment an easy win for Team Red, given they already have excellent power scaling characteristics on low-TDP designs beforehand.
