When AMD announced 7nm Ryzen was coming at CES 2019, sharp-eyed readers immediately noticed that there was room on the die for two 7nm chiplets, not just one. The possibility of a 16-core Ryzen 7 built on 7nm instantly became the worst-kept secret of the product family. When AMD provided additional detail on the CPU at Computex, however, the product stack appeared to top out at just 12 cores — less than the 16 that were theoretically possible.
AMD, it turns out, was just holding back the last product in the new 7nm Ryzen 3000 family to put a bit of polish on it for E3. While this CPU won’t be launching in July, it’ll bring a full 16 cores to the Ryzen desktop family. Meet the Ryzen 9 3950X.
Back in May, when clock speeds for an engineering sample 16-core Ryzen leaked, we noted that the chip’s relatively low clocks (3.3GHz base, 4.2GHz boost) could be the result of keeping ES clocks lower than shipping parts (a common industry practice) or because AMD wanted to limit the TDP of the part to keep it within the capabilities of the AM4 standard. We can see both goals reflected in the product’s final specs.
Remember, TDP is typically calculated based on base clock, not boost clock, and while AMD CPUs
have been better of late at staying within their listed TDPs, this is not an absolute requirement given that boost clocks are frequencies the company doesn’t promise will be available in all situations.
If you examine the size of the gap between AMD’s base and boost clocks across its entire product portfolio, you’ll note that the lower-end chips with smaller core counts maintain a 1.16x gap between base and boost clock. The Ryzen 3600, 3600X, and 3800X all have a gap roughly this size. The Ryzen 7 3700X has a slightly larger gap to create differentiation between itself and the Ryzen 7 3800X, which results in a 1.22x gap. The 12-core Ryzen 9 3900X has a similar spec. The Ryzen 9 3950X, on the other hand, has the largest difference between base and boost clock, with a 1.34x difference between the two parts.
The implication here is that the Ryzen 9 3950X probably sticks to a lower frequency at higher core count load compared with other parts, in order to stick within its 105W TDP. This, in turn, could indicate that AMD will keep a 16-core Threadripper CPU as part of the product stack when it eventually launches those parts at some point in the future. Threadripper TDPs have always scaled up much higher than Ryzen (the existing 2950X is a 180W part), which could give AMD more headroom to raise the base clock by a few hundred MHz.
There also may be scaling differences in applications due to the limited amount of memory bandwidth available to all 16 CPU cores. Ryzen 3000’s doubled L3 cache will help relieve bandwidth pressure, but this is something we’ll have to test to speak to the performance impact. The most we can say at the moment is that it would not be surprising if 8C – 16C scaling was less effective on a Ryzen 7 platform compared with a Threadripper platform, at least in certain applications.
AMD announced at E3 that the 3950X would be available in September for $749.
AMD Announces 16-Core Ryzen 9 3950X 7nm Desktop CPU - ExtremeTech
