Deep Dive on Zen 5 Mobile Architecture Confirms 16% IPC Over Zen 4

AMD announced revamped Zen 5 processors at Computex in May for desktop and mobile, but they won’t launch until July. Ahead of their auspicious debut, we now have our first deep dive into Zen 5 mobile, and it verifies AMD’s claim of an IPC (instructions per clock) gain over Zen 4 of 16%.
David Huang procured the second-rung Zen 5 mobile CPU via a loaner laptop from a friend who works in the supply chain. This chip is the 10-core Ryzen AI 9 365, and there is also a CPU above this one in the product stack—the Ryzen AI 9 370HX, which features 12 cores. He says he only had a few hours with the laptop, so he ran some basic tests to measure its chops. He notes that as an engineering sample, things might be different when retail laptops arrive next month. This CPU features four Zen 5 cores and six smaller Zen 5c cores.
Overall, he says the test results in Geekbench show the IPC gain over Zen 4 is around 15% to 17%, so AMD was right on the money with its claim of 16%. Mr. Huang also notes that Geekbench is a relatively short test for a CPU to endure, so he also ran some Spec CPU 2017 tests. Those results varied, ranging from a 24% uplift to 5% slower than Zen 4 in some tests. AMD’s original claim was in reference to the desktop chips, so we don’t precisely know what the mobile chips’ uplift is compared with Zen 4. However, according to these tests, it should also be in the same range.
Huang states that the mobile version of Zen 5 has several significant improvements over Zen 4, specifically in multi-threading. Still, it will have an “unprecedented” delta in performance compared to the desktop version due to several reasons. One of the biggest is that the Zen 5c cores get a minuscule amount of cache to share at just 8MB, and the regular Zen 5 cores get just 16MB, which is half the amount bestowed upon the desktop chips. The desktop chip also gets a 5.7GHz maximum boost clock, which is reduced to 5.1GHz on the mobile part. In addition, the mobile part has its SIMD throughput and L1 vector load bandwidth halved.
We’ll have to wait until retail laptops are sent to media to see how these hybrid CPUs compare to their biggest rival, the Qualcomm X Elite and Plus chips now shipping in Copilot+ PCs. Intel’s challenge to Zen 5 will be Lunar Lake, also announced at Computex but won’t be launched until later this year.
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