Thursday, 8 October 2020

AMD’s Zen 3 Drops November 5 With Major IPC Enhancements

At its Zen 3 launch event today, AMD’s Lisa Su, Mark Papermaster, and Robert Hallock collectively demoed what looks like the most impressive CPU AMD has launched since Zen 1, back in April 2017. That’s saying something, considering that Zen+ and Zen 2 were no slouches themselves.

AMD is predicting a 1.19x IPC uplift for Zen 3 over last years’ Zen 2 architecture. This improvement is coming, as was rumored, from some fundamental changes to the CPU architecture. Instead of the classic, quad-core CCX with two CCX’s on a single chiplet, AMD has created a unified CPU design with all eight cores sharing a single 32MB L3 cache.

There are several significant things about this change. Prior to Zen 3, AMD didn’t really have a 32MB L3 cache. Rather, it had two 16MB L3 caches, each backed up by a quad-core Ryzen CPU. That’s not a perfect comparison, because in this case, each quad-core could access the L3 partition of the other, but the performance penalty for doing so was non-trivial. Now, there’s a unified core cluster and the performance improvements that come along with it — plus an unspecified number of performance gains from what Mark Papermaster called “a total, front-to-back redesign” with “end-to-end improvements in caching, load-store, prefetching, dispatch, and decode.” Execution units are now wider and AMD has implemented a feature it calls “Zero Bubble” to hide latency.

The benchmarks AMD showed claim a 1.19x IPC uplift overall and a 1.26x uplift over Zen 2 / Ryzen 3000 CPUs in 1080p gaming. While we don’t assume that any company is being 100 percent accurate in its benchmark disclosures, AMD has been quite honest over the past three years about what kind of performance reviewers should expect to see out of Ryzen compared to what ships out the door.

Pricing Bumps Up

This 1.19x improvement isn’t going to come quite as cheap, this time around. AMD is launching a Ryzen 5 5600X, a Ryzen 7 5800X, and the Ryzen 9 5900X, with 6, 8, and 12 cores respectively. As we expected, and contrary to the rumor mill’s predictions, AMD did not launch a 10-core chip at this event.

This time around, the CPUs are coming in slightly above the MSRP’s their predecessors offered. The 5600X is $299, the 5800X is $449, and the 5900X is $549. This represents an increase of ~$50 on all parts relative to Zen 2’s launch pricing, and it’s a higher price for the Ryzen 5 family than AMD has charged before. The Ryzen 7 5800X remains cheaper than the debut price of the Ryzen 7 1800X ($449 versus $500). 12 cores are harder to compare, because prior to the 3900X, AMD’s 12-core chips required a Threadripper platform and were more expensive as a result. AMD’s 5900X is $50 more expensive than the 3900X, but still far cheaper than the $800 launch price of the Threadripper 1920X.

Assuming AMD delivers the performance it is promising, the Ryzen 5 5600X will keep its price/performance ratio — a 1.2x increase in price is canceled out (in that metric) by the 1.2x improvement in performance. Both the 5800X and 5900X actually improve their price/performance ratios, despite being more expensive — the 5800X is 1.3x more expensive over the 3800X and 1.2x faster, while the 5900X is 1.11x more expensive and (again, assuming AMD’s numbers hold up) 1.2x faster.

AMD is claiming the Zen 3 microarchitecture is better for gaming than Intel Core, which is a claim we’ll dig into once we have chips. If true, it represents the decimation of Intel’s last high-end, consumer-focused, hold-out category. AVX-512 would be the last major feature or capability Intel offers that AMD doesn’t match, and AVX-512 support isn’t common in the consumer market.

Oh, and one more thing. While we don’t have a die shot, the 16-core 5950X is coming to market on November 5 with a 4.9GHz maximum turbo clock, the same 1.2x IPC uplift, and a price of $800.

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