AMD is reportedly planning a new Zen core design starting with Zen 6, made using a puzzle of parts from previous Zen architectures. The aim seems to be greater power efficiency, all while using less silicon area.
According to @InstLatX64 on X, AMD could introduce a third core design with its upcoming Zen 6 architecture, called Low Power. This core type is to be available alongside the traditional/classic Zen 6 and the dense Zen 6c variants. Unlike the latter, which focuses on squeezing more cores into the same die area while maintaining a similar overall design to the standard cores, Zen 6 LP (Low Power) is said to borrow different blocks of previous architectures to build a highly power-efficient core, without developing everything from the ground up.
Again, according to @InstLatX64, Zen 6 LP would combine:
- Zen 6 ISA (Instruction Set Architecture), i.e. what software sees, meaning Zen 6 LP cores should support the same instruction set and features as classic Zen 6 cores.
- Zen 5 uArch (short for microarchitecture), i.e. how the CPU internally executes instructions, which hints that Zen 6 LP’s branch predictor, scheduler, execution engine, etc., are largely derived from Zen 5 rather than the newer Zen 6.
- Zen 4 FPU (Floating Point Unit), which could mean support for AVX-512 instructions using two 256-bit operations rather than one native 512-bit datapath.
- Zen 3 L2 Cache, i.e. 512KB of cache per core instead of the 1MB L2 per core since Zen 4, which suggests that AMD is prioritising die area, because cache takes a good chunk of silicon.
- Zen 2 L3 Cache, specifically, Zen 2 Mendocino mobile APUs, which packed only 1MB of L3 per core instead of 4MB in regular Zen 2. This should significantly reduce die area, all while improving power efficiency.
Needless to say, Zen 6 LP, if real, will be one of the most frankensteined designs made by AMD, mixing and matching existing blocks to presumably reduce engineering time and cost, all while presenting itself as regular Zen 6 to the software layer.
But that’s not all; according to another rumour from @Gotou_kai3 on X, these Zen 6 LP cores could match or exceed Zen 5 LP. Since Zen 5 doesn’t have a Low Power version, the leaker probably meant Zen 5c. Regardless, considering the reduction in cache area, Zen 6 LP shapes to be a highly efficient design, both in terms of power and in silicon consumption.
If these cores end up being used in a consumer CPU, we can expect them to be found on power-constrained devices like laptops and handhelds, and less on desktops, since Zen 6c would do the job just fine. But as usual, all of this is just rumour talk, and nothing is certain until AMD officially reveals it. The company has already introduced its Zen 6 and Zen 6c cores during the Epyc 9006 CPU family launch, but it didn’t mention anything about Zen 6 LP so far.
