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Our Tests Show Not All Ryzen 3000 Cores Are Created Equal

Thoughts

The new Ryzen 3000-series chips come with a mix of faster and slower cores, some of which cannot reach the rated single-core turbo speeds, which is a notable change from what we normally expect from desktop processors. The semiconductor industry is experiencing new challenges as engineers grapple with the fundamental issues of scaling down to smaller process nodes. In some cases, we can expect to see clock regressions as transistors shrink further. We could also see more variation in die yields, among many other factors. It appears that AMD is circumventing some of those issues by optimizing its binning process rather than allowing it to be reduced to the lowest common turbo bin. This tactic isn't entirely unheard of, we've already seen this trend emerge with some mobile processors, but it appears to now be making its way to the desktop PC.

You can view this in several ways. Some will view this as smart utilization of the silicon that AMD has to work with. AMD has apparently made some tradeoffs to deliver chips with a smaller geometry to market faster than its competitor, and it has used clever engineering at both the silicon and software level to pull off the feat. The more the software knows about the hardware underneath, the better.

But this does open up another line of questions. How does AMD decide what the minimum bar for a 'slow' core is? Logic dictates that would be the base frequency of the chip, but that would theoretically mean some cores on a 3600X would only operate at 3.8 GHz.

How much variation can we expect in the cores of chips purchased at retail? How would the binning impact performance in systems where the software optimizations aren't installed, or if the scheduler doesn't profile all workloads correctly even when it is installed? That could lead to erratic performance characteristics as workloads fall into slower cores. In our testing, we did observe that in some cases, but we caution that these results come from a single sample. It's hard to make definitive declarations with a sample size of one, especially given some of the small frequency variations we observed between cores. But AMD did confirm some of our findings.

We asked AMD if some cores are faster, and if the minimum requirement for a core is to reach the base frequency, to which AMD responded:

There are faster cores, as noted in Ryzen Master. All AMD processors are tested to ensure boost clocks and performance across various workloads meet the product definition.

Technically, AMD's only specified boost clock applies to a single-threaded workload, which you could argue means AMD only has to deliver a single core capable of delivering the maximum frequency. But, if there are several slower cores that can only reach the base frequency, that would surely impact performance in various multi-threaded workloads. We hope that AMD provides more clarity in the days to come.

Intel says that all of its cores are capable of reaching the Turbo Boost 2.0 specification outlined on its spec sheet. The company has complemented that base level of turbo performance with its Turbo Boost Max 3.0 feature on its HEDT chips, which, much like AMD's implementation, targets workloads at faster cores. Theoretically, if Intel accepted similar trade-offs in its binning process, would 10nm processors already be shipping? Or, has Intel already decided to make these adjustments on future products? We aren't sure of the answer to either of those questions, but it is food for thought.

This shift in AMD's policy could foreshadow broader changes for the industry in the future. AMD's binning could also improve as the 7nm process matures, but that will be hard to determine with no public-facing specifications for slower cores.

Our testing revealed several interesting facets, but we have much more to learn. For instance, the Ryzen 5 3600X comes with two cores disabled, which might be due to the normal defects that occur during manufacturing, but perhaps some of the cores didn't meet a performance specification that is unknown to us. It will be interesting to profile chips with all eight cores active to see how they measure up. Not to mention the 12-core Ryzen 9 3900X. We'll certainly be busy at our test benches.

Modern processors are certainly a marvel, but they are also mind-bendingly complex. Core parking, power gating, thermals, power delivery, and power density, among many other variables, can all impact performance and testing. Measurement tools can, too. We've done our best to ensure a stable test environment (thanks to Ian Cutress at AnandTech for a sanity check), but this is, in some respects, uncharted territory. You could experience different results than ours.

In the end, performance boils down to the results you see during your daily use. We recently gave the Ryzen 5 3600X an Editor's Choice award with testing based off this very processor, which we purchased at retail. There is no doubt these chips are capable performers, but there is much to learn about this new definition of what we can expect from the individual cores in our systems, even though it actually isn't defined at all.

Image Credits: Tom's Hardware, AMD


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Paul Alcorn

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