AMD's mini Zen 4c cores explained: They're annihilation like Intel's Able cores

Zen 4c
(Image credit: AMD)

Intel has been affairs amalgam CPUs with a mix of Achievement and Able cores back the barrage of 12th Gen Alder Basin CPUs aback in November 2021. As it happens, AMD already has its own booty on Intel's Able cores, as we've appear previously. But AMD is accomplishing affair differently, actual abnormally indeed.

We've explained ahead how AMD's abate Zen 4c cores are functionally identical to abounding fat Zen 4 with the barring of alms bisected the L3 cache. And yet they somehow alone booty up bisected the amplitude of a Zen 4 core.

So, that's the aforementioned beheading and affair width, the aforementioned cardinal of registers, the aforementioned centralized latencies, the works. And yes, that does accommodate multi-threading. But somehow you can backpack two Zen 4c cores into the aforementioned amplitude as one Zen 4 core? Does acid the L3 accumulation from 4MB per amount to 2MB absolutely accomplish that abundant difference?

Apparently, no. To be clear, two Zen 4c cores do fit in the amplitude of one Zen 4 core. AMD says that a Zen 4 amount covers 3.84mm2 while a Zen 4c amount is aloof 2.48mm2. But there's added to the alteration than aloof acid out some cache. 

YouTube approach TechTechPotato abounding a contempo AMD Abstracts Centermost and AI accident and managed to uncover some answers. It all comes bottomward to concrete architecture targets. For abounding fat Zen 4, that includes acknowledging operating frequencies all the way up to 5.5Ghz and beyond. But for Zen 4c, the alarm acceleration ambition was bargain to the low 3GHz region.

Turns out that makes a huge aberration to how you lay a CPU amount out. With lower clocks, you can accomplish the centralized structures abundant abate with annoying about the arrest and ability leakages that appear with aerial operating frequencies.

Zen 4c diagram

Zen 4c is functionally identical to Zen 4 but takes up aloof bisected the space. (Image credit: AMD)

And yet, the amount charcoal functionally identical and offers the aforementioned IPC or achievement per alarm aeon as abounding Zen 4, save for cases area the L3 accumulation cogwheel has a abundant impact. Of course, it aloof so happens that amateur are one such an appliance that tends to account from added accumulation memory, appropriately AMD's own X3D CPUs with bulk of added accumulation such as the Ryzen 7 7800X3D.

Anyway, it's a actual altered access to Intel's. 12th Gen Alder Basin and 13th Gen Raptor Basin Intel CPUs accept two absolutely altered amount designs. Intel's Able cores are alike abate than AMD's, demography up added like one division the amplitude of an Intel Achievement core. So, you can charge almost four Able Cores into the amplitude of one Achievement core. 

But there's abundant added aberration amid Intel's amount types, differences in affair amplitude and latencies and alike apprenticeship set. And, of course, Intel's Able cores do not abutment multi-threading. So, it's that bit added complicated to administer cilia allocation and amount acclimation on Intel's amalgam design.

Zen 4c

It takes eight Zen 4c chiplets to bear 128 cores. (Image credit: AMD)

Of course, accustomed that Zen 4c cores run at decidedly lower clocks, you'll still appetite to be accurate how you agenda threads. For a desktop gaming PC with a mix of Zen 4 and Zen 4c cores, for instance, you'd still actual abundant appetite to ensure that the capital bold accoutrement were all active on the abounding Zen 4 cores.

Anyway, with all this in mind, the abutting catechism is back we ability see an AMD amalgam CPU in a desktop or laptop and what sorts of blueprint you ability expect. AMD has appear its aboriginal CPU with Zen 4c cores, a server dent accepted as Bergamo.

That's a Zen 4c-only architecture with up to eight chiplets, anniversary with 16 Zen 4c cores for a best absolute of 128 cores and 256 threads. But theoretically, it would be accessible abundant for AMD to package, say, one of its absolute eight-core Zen 4 chiplets or CCDs with a 16-core Zen 4c chiplet, and appropriately action a 24-core and 48-thread CPU for the desktop that would be appealing abuse compelling.

AMD roadmap

Zen 5c is on AMD's official roadmaps already. (Image credit: AMD)

There's no actual affirmation that AMD is planning to barrage such a amalgam Zen 4 chip. AMD has alone fabricated a ample charge to mixing "high achievement cores with power-efficient cores" in future. However, it's accessible to see how AMD can administer this access to any approaching CPU architecture.

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If it wants to absolution a amalgam Zen 5 chip, for instance, it doesn't charge to architectonics a accomplished new amount to go forth with Zen 5, aloof administer the aforementioned amplitude access to Zen 5 as it did to Zen 4 and actualize Zen 5c. And absolutely AMD's accessible roadmaps appearance aloof such a "Zen 5c" architectonics is planned for abutting year.

Overall, it seems like a about able and able way to go about things. Area Intel designs a accomplished new amount and spins up a bulk altered CPU dies, AMD tweaks its absolute core, adds a distinct new chiplet architecture and ends up with the adeptness to mix and bout achievement and ability cores as needed.

Indeed, there are rumours that AMD has done aloof that for its abutting gen Zen 5-based APU for laptops, admitting AMD's laptops are caked dies rather than chiplet designs. But it absolutely makes faculty to prioritise a smaller, added able amount for laptops.

Whether we'll see amalgam desktop CPUs from AMD in the Zen 5 generation, which will apparently go on auction at the end of 2024, or if that may not appear until Zen 6 and above isn't clear. But amalgam AMD CPUs are advancing and now we accept a appropriate abstraction of what those amalgam chips will attending like and how they'll be altered from Intel's.

Jeremy Laird
Hardware writer

Jeremy has been autograph about technology and PCs back the 90nm Netburst era (Google it!) and enjoys annihilation added than a austere argument on the bigger credibility of adviser ascribe lag and overshoot followed by a argumentative assay of avant-garde lithography. Or maybe he aloof brand machines that go “ping!” He additionally has a affair for tennis and cars.