AMD to begin disclosing Ryzen Zen 4c clock speeds and list the missing core counts on official spec pages — much-needed change will bring the company in line with standard industry practices

(Image credit: Fritzchens Fritz)

The arrival of AMD's Zen 4c cores to its lineup of consumer chips has brought new levels of core density and power-optimized performance to the company's portfolio. But AMD hasn't adhered to standard industry practice and divulged clock speeds for the new cores in any fashion. In fact, even the very presence of the smaller and less-performant Zen 4c cores has been absent from the company's main specification pages and marketing materials, leading to claims of deceptive marketing practices.

We asked AMD about the lack of clear communication around the new tech at its recent AI day, at which time the company told us it would review the policy. When we followed up a few weeks later for an update: AMD now tells Tom's Hardware it will begin divulging these specifications and displaying them more prominently in its materials, with the first updates to its website coming soon.

As with Intel's E-cores, AMD's Zen 4c cores are designed to consume less space on a processor die than the 'standard' performance cores (in AMD's case, Zen 4), while delivering enough performance for less demanding tasks, thus saving power and delivering more compute horsepower per square millimeter than was previously possible (deep dive here). But the similarities end there. Unlike Intel, AMD employs the same microarchitecture and supports the same features with its smaller cores. Still, they do operate at lower clock rates and thus offer less peak performance than standard cores.

AMD currently has five consumer chips with its Zen 4c cores on the market, and the company takes the same approach with all of its listings for these chips. As shown in the image album above, AMD doesn't divulge the presence of the smaller Zen 4c cores on its main specifications page — you have to navigate to a secondary 'Full Specifications' page to even find a mention that the chips have Zen 4c cores. And even here, the listing is ambiguous. Most mainstream customers likely won't know what a "2 x Zen4, 4 x Zen4c" listing means, especially since this sole entry is listed in an 'architecture' row and not clearly listed as pertaining to core counts.

The lack of mention of the Zen 4c core counts on the standard spec page is particularly concerning because most retailers might not include the full specifications in their own listings. That could lead to deceptive product listings at retailers.

As you can see in the third slide, AMD also doesn't list the presence of Zen 4c cores in its marketing materials — the Ryzen 5 8540U and Ryzen 3 8440U both come with Zen 4c cores, but that isn't mentioned anywhere in AMD's presentations for its new Ryzen 8040 series processors. Instead, we only found out this detail after AMD posted the spec pages after the launch event. This is particularly concerning with the Ryzen 3 model, as it only has one standard Zen 4 core paired with three less-performant Zen 4c cores.

Additionally, unlike Intel's disclosures with its E-cores, where the presence and clock rates are prominently listed on all spec pages, AMD doesn't divulge Zen 4c clock rates at all — you won't find them anywhere. AMD tells us that “today, we divulge base [frequency] across the core spectrum, and max [frequency] across the core spectrum.” This means that while the processor's base frequency is ostensibly derived from the Zen 4c cores, the processor's maximum frequency is a listing of the standard Zen 4 core. Changes to these clock rates, particularly when AMD releases its next-gen products, will alter the fundamental performance characteristics of the chip, so disclosure is important.  

Intel takes a different approach to its E-core strategy, with clear listings of both types of cores and clock rates in all of its marketing materials and specification pages (see the last image in the above album).

How did AMD's lack of disclosure come to be? Given that AMD also doesn't list its Ryzen AI engine clock rates, we asked the company at its recent launch event if this practice of not disclosing important specifications is becoming a trend:

“We're not trying to create a trend. But we need to check what we disclose and take the feedback going forward, look at both our own approach, and competitively, how we want to present that," the representative responded. "The one thing I'll say in our architecture is that the dense (Zen 4c) versus the E-core is very different in its capability, so we're not trying to describe those as apples-to-apples."

I agree with the point that AMD's approach to its x86 hybrid strategy isn't the same as Intel's E-core approach — in many respects, such as delivering the same IPC and instruction set support for both types of cores, AMD's approach is superior and makes a lot more sense, thus avoiding the numerous stumbles Intel had as it implemented two different core microarchitecture in its products.

However, while Zen 4c is arguably a superior approach and inarguably a result of incredibly clever engineering, the space-optimized Zen 4c cores do operate at slower speeds than standard cores, and AMD's customers deserve clear communication about the specifications of the product they're buying.

We followed up with AMD after the event, and it says it will begin disclosing Zen 4c clock rates soon. It will also incorporate the number of Zen 4c cores into its main product specification listings, both of which are welcome improvements. The first step is to prepare its website to accommodate the new listings, an effort we are told is currently underway and is expected to take roughly a few weeks. We'll follow up on this topic when the listings become active.

Paul Alcorn
Managing Editor: News and Emerging Tech

Paul Alcorn is the Managing Editor: News and Emerging Tech for Tom's Hardware US. He also writes news and reviews on CPUs, storage, and enterprise hardware.

  • Co BIY
    This is a great piece of tech Journalism !

    Thank You.
  • ET3D
    The only difference between all Zen 4 and a mix of Zen 4 and Zen 4c is the mix of clock boost behaviour. That's something that we don't normally get, unless it's tested by reviewers. All the maximum Zen 4c clock will tell us is that when using more than 2 cores (in a 2+4 configuration), the extra cores will have a certain maximum speed. That's somewhat useful, but a lower boost is expected for any CPUs, regardless of AMD or Intel or number of cores. When going up in the number of cores used, CPUs will drop clock speed anyway.

    So while the Zen 4c maximum clock speed is of theoretical interest, it's not of any practical interest unless we know the clock behaviour of other devices, which we are unlikely to get because articles like this one focus on getting the less important specific spec rather than asking for better disclosure of clock behaviour.
  • abufrejoval
    I understand their hesitancy.

    These chips today are extremely complex beasts as they try to exploit every nook and cranny for an extra bit of performance. And to explain these things to the level of detail that people are satisfied there are no longer hidden snags, would require bringing the audience to the level where they might have been part of the design team.

    And not everyone who just loves to complain or start conspirational rumors will want to or be able to get there.

    The logic for mixed 4 and 4c cores in TDP limited designs isn't that different from choice for the Ryzen 9 7950X3D to use a mix of CCDs. By the time you've exhausted the heat budget all the non-V-cache cores in the "fast" CCD, the fact that the cores in the V-cache CCD won't be able to reach non-cache peaks is no longer relevant, because with all cores active, everbody will have to take fewer Watts from the power faucet and reduce clocks anyway. It should work out to a very small clock disadvantage overall at 16 fully active cores.

    Here with ~15 Watt total power budgets it's somewhat similar: when say in a 2(4)+6(4C) setup the 3rd core get loaded, the faster cores may have to clock down anyway to reduce their part of the total to a point where they are running at very similar clocks to what the 4C cores can sustain as max speeds. The extra dark silicon area that the high-frequency cores need for heat dissipation at their top frequencies doesn't deliver any benefit when the heat doesn't peak the same on the C-cores. Apart from the cache sizes (which probably still differ), there should be no measurable impact on performance, just more dies per wafer.

    Of course the optimal relationship between 4 and 4C cores varies with the Watt budget available and the workloads being run.

    With Intel P- and E-cores and with the various ARM core designs things are far more complicated, because there are Watt budgets where an E-core might actually be faster than a P-core for a given workload. And then there are Watt budgts where P-cores simply no longer function, while E-cores still do.

    And that is because these cores are actually very different CPU designs, different transistor types, and in the future even with different fab process sizes.

    It means with every additional bit of information, there is more opportunities to get it all wrong: accidentally or also intentionally.
  • thestryker
    Just a guess based on what's been spoken of publicly is that AMD didn't really want to disclose the Zen 4c boost clocks because they're going to be a lot lower than Zen 4. AMD has been pushing that nobody would know the difference between Zen 4 and Zen 4c, and that's likely because the all core boost of all Zen 4 vs a mix is probably very close to the same in limited TDP circumstances. AMD doesn't disclose their all core boost speeds though so without that information it would appear as though AMD is lying about the performance.

    I look forward to their disclosure just the same as more transparency the better.
  • _Flare
    As far as AMD disclosed to this day, Zen4c vs Zen4 is only compactified and the L3-Cache has mobile-grade size like mobile Zen3 or Zen4 has, so for each 8-Core CCX 16MB instead of the desktop-grade 32MB L3.
    L1, L2 and every other capability is equal, max turbo excluded.
    The compatification results in a denser core obviously and because of physics those have lower max turbo.

    So in my opinion all AMD need to add is the max turbo of the Zen4c cores.
    Same opinion is also for the X3D CCDs max turbo in the 7900X3D/7950X3D.
  • Moobear
    Ugh very unpleasant read very negative point of view had a bad day??? Unbelievable. quote: But the company hasn't adhered to standard industry practice and divulged clock speeds for the new cores in any fashion. In fact, even the very presence of the smaller and less-performant Zen 4c cores has been absent from the company's main specification pages and marketing materials, leading to claims of deceptive marketing practices. AMD will let us know don t flip, and just my 2 cents I m happy AMD doesn t adhere to standard industry practice, this whole piece could have been alot shorter and a more relevant informative piece without al the assumptions. But yeah have a great day.
  • jlake3
    While a breakdown of Zen 4/4c cores would definitely be good, the clockspeed issue feels more academic than practical? Under a hard single core load you're going to be limited by the boost of the strongest core, while under a sustained load I'd assume you're not running all cores at maximum boost clock anyway.

    As for the NPU... is the clockspeed a meaningful spec? I thought software support and TOPS was important, and whether you got there through more clocks or more parallelism wasn't really important at this level.
  • usertests
    AMD is finally disclosing the clock speeds. But why are there 3 base clock speeds listed?

    Base Clock(ℹ️)
    (Represents the average effective base frequency of all cores.)

    That's stupid and if there's follow-up reporting it should mention this useless number.