Thursday, November 2nd 2023
AMD Introduces Ryzen 5 and Ryzen 3 Mobile Processors with "Zen 4c" Cores
AMD today launched its first client processors that feature the compact "Zen 4c" CPU cores, with the Ryzen 5 7545U and Ryzen 3 7440U mobile processors for thin-and-light notebooks. The "Zen 4c" CPU core is a compacted version of the "Zen 4" core without the subtraction of any hardware components, but rather a high density arrangement of them on the 4 nm silicon. A "Zen 4c" core is around 35% smaller in area on the die than a regular "Zen 4" core. Since none of its components is removed, the core features an identical IPC (single thread performance) to "Zen 4," as well as an identical ISA (instruction set). "Zen 4c" also supports SMT or 2 threads per core. The trade-off here is that "Zen 4c" cores are generally clocked lower than "Zen 4" cores, as they can operate at lower core voltages. This doesn't, however, make the "Zen 4c" comparable to an E-core by Intel's definition, these cores are still part of the same CPU clock speed band as the "Zen 4" cores, at least in the processors that's being launched today.
The Ryzen 5 7545U and Ryzen 3 7440U mobile processors formally debut the new 4 nm "Phoenix 2" monolithic silicon. This chip is AMD's first hybrid processor, in that it has a mixture of two regular "Zen 4" cores, and four compact "Zen 4c" cores. The six cores share an impressive 16 MB of L3 cache. All six cores feature 1 MB of dedicated L2 cache. There is no complex hardware-based scheduler involved, but a software based solution that's deployed by AMD's Chipset Software, which tells the Windows scheduler to see the "Zen 4" cores as UEFI CPPC "preferred cores," and prioritize traffic to them, as they can hold on to higher boost frequency bins. The "Phoenix 2" silicon inherits much of the on-die power-management feature-set from the "Phoenix" and "Rembrandt" chips, and so are capable of a high degree of power savings with underutilized CPU cores and iGPU compute units.
The iGPU of "Phoenix 2" is based on the latest RDNA3 graphics architecture, however it is not exactly built for gaming, it has just enough muscle for a modern Windows 11 experience with animated UI, complex web-pages, and streaming video based on the latest AV1 and HEVC formats. The iGPU packs 4 compute units that add up to 256 stream processors. There are also AI accelerators that are intrinsic to the RDNA3 compute units. A big change with "Phoenix 2" is that it lacks the 16 TOPS XDNA accelerator, and hence both the processor models being launched today lack Ryzen AI.
As for the chips themselves, the Ryzen 5 7545U maxes out the "Phoenix 2" silicon, enabling all two "Zen 4" and all four "Zen 4c" cores; along with 16 MB of L3 cache, 22 MB of "total cache" (L2+L3), a CPU clock speed of 3.20 GHz base, and 4.90 GHz boost; and a TDP band of 15 W to 30 W. The Ryzen 3 7440U, on the other hand, is a quad-core chip, enabling both "Zen 4" cores, and two out of the four available "Zen 4c" cores. The shared L3 cache is reduced to 8 MB, and hence the total cache is down to 12 MB. The CPU is clocked at 3.00 GHz, with 4.70 GHz maximum boost. The TDP band remains 15 W to 30 W. Both models max out the iGPU with its available 4 compute units; which has the branding Radeon 740M.
Notebooks based on the Ryzen 5 7545U and Ryzen 3 7440U should begin rolling out now, the two chips mostly cater to entry/mainstream variants of existing thin-and-lights, including some notebooks with mainstream thickness.
The complete press-deck follows.
The Ryzen 5 7545U and Ryzen 3 7440U mobile processors formally debut the new 4 nm "Phoenix 2" monolithic silicon. This chip is AMD's first hybrid processor, in that it has a mixture of two regular "Zen 4" cores, and four compact "Zen 4c" cores. The six cores share an impressive 16 MB of L3 cache. All six cores feature 1 MB of dedicated L2 cache. There is no complex hardware-based scheduler involved, but a software based solution that's deployed by AMD's Chipset Software, which tells the Windows scheduler to see the "Zen 4" cores as UEFI CPPC "preferred cores," and prioritize traffic to them, as they can hold on to higher boost frequency bins. The "Phoenix 2" silicon inherits much of the on-die power-management feature-set from the "Phoenix" and "Rembrandt" chips, and so are capable of a high degree of power savings with underutilized CPU cores and iGPU compute units.
As for the chips themselves, the Ryzen 5 7545U maxes out the "Phoenix 2" silicon, enabling all two "Zen 4" and all four "Zen 4c" cores; along with 16 MB of L3 cache, 22 MB of "total cache" (L2+L3), a CPU clock speed of 3.20 GHz base, and 4.90 GHz boost; and a TDP band of 15 W to 30 W. The Ryzen 3 7440U, on the other hand, is a quad-core chip, enabling both "Zen 4" cores, and two out of the four available "Zen 4c" cores. The shared L3 cache is reduced to 8 MB, and hence the total cache is down to 12 MB. The CPU is clocked at 3.00 GHz, with 4.70 GHz maximum boost. The TDP band remains 15 W to 30 W. Both models max out the iGPU with its available 4 compute units; which has the branding Radeon 740M.
The complete press-deck follows.
54 Comments on AMD Introduces Ryzen 5 and Ryzen 3 Mobile Processors with "Zen 4c" Cores
Zen 4 and Zen 4c are BOTH high performance cores and are BOTH designed for high efficiency.
Also E cores are die-area efficient. In terms of power efficiency Intel thinks of their cores as AMD does, they're all efficient.
How does it do that with 35% less silicon?
Basically they traded clockspeed headroom for less die space and greater efficiency at the low end of TDP.
Zen 4c: AMD’s Response to Hyperscale ARM & Intel Atom (semianalysis.com)
"16 Zen 4c cores are barely larger than 8 Zen 4 cores. At ISSCC 2023, AMD disclosed Zen 4’s CCD to be 66.3mm². This is the design area without die seal and scribe lines at the edges. Zen 4c’s CCD design area is just 72.7mm², not even 10% bigger!"
IIRC, it does have slightly limited L3 Cache bandwidth, and half the l3/core of desktop Zen 4 - but the same as Laptop Zen 4.
The ideal would be Zen4c vs Zen4.
The way i see it, intel had a cpu with high and low power cores for desktops/laptops or whatever, this is AMD's answer to that, disagree or not.
Zen 4c are fabbed on TSMC 4nm which is a density optimized 5nm. Zen 4c cores also have half the L3 cache the normal zen4 cores have. Cache takes up a lot of area.
EDIT: Theres conflicting articles going around, some say they are on 4nm. Some say its still 5nm. Either way, majority of that area improvement is reduction in cache. Clock freq dont impact area much, so the reduction in clk freq is not really contributing to area reductions.
The library AMD is using is also different with density being priority so everything in that library can be packed closer, routing layers routed closer together via rules, etc.
Cache size reduction is not the major contributor of the size reduction.
Frequency target is part of the design.