One of the biggest surprises Intel revealed when it announced its Lunar Lake architecture was its decision to remove Hyper-Threading Technology (SMT) from its next-generation gaunt and lightweight architecture. New Zen 5/Zen5C Multithreading Benchmarks Fornix suggest that this feature still benefits AMD processors, showing significant performance and efficiency gains by using two threads on a single core.
Phoronix tested the AMD Ryzen AI 9 HX 370 in Linux with four Zen 5 cores and eight Zen 5c cores, all with simultaneous multithreading (SMT) capabilities. The Linux-focused outlet tested the chip with SMT, turning it on and off in various tests in Ubuntu 24.04 to see the advantages (or disadvantages) of AMD’s SMT.
All 57 benchmarks showed a performance advantage with SMT enabled. On average, the Ryzen AI 9 HX 370 ran 18% faster using SMT than the same benchmarks without SMT. Some benchmarks even performed better than 18% using SMT, showing a whopping 67% performance advantage on the toyBrot Fractal Generator benchmark.
Power draw was also virtually unchanged when SMT was enabled. Phoronix recorded an average power draw of 19.27 watts with SMT disabled on the Ryzen AI 9 chip, and 19.63 watts with SMT enabled, which translates to a paltry 2% impact on power with SMT enabled. Temperatures were also unchanged, with the chip running at identical temperatures with SMT enabled and disabled.
Phoronix’s tests show that Zen 5 and Zen 5c benefit greatly from multi-threading technology. In the case of the Ryzen AI 9 HX 370, AMD gives up only 2% of its power to extract an impressive 18% more performance from the system, significantly improving efficiency.
Ironically, Intel removed Hyper-Threading in Lunar Lake to improve performance. Its next-generation Lion Cove P-cores for Lunar Lake lack Hyper-Threading, so it relies on its much faster next-generation E-cores to make up for the loss. Intel claims that removing Hyper-Threading allowed its designers to squeeze a 30% performance improvement per watt per area out of the Lion Cove P-cores.
Another criticism Intel has made of Hyper-Threading technology was that it was only used as a last resort in its outgoing hybrid CPU architectures, where secondary threads on the P-cores were only used once the E-cores were fully saturated. This was reportedly another reason why Intel abandoned Hyper-Threading technology in Lunar Lake.
Nevertheless, Phoronix’s tests confirm that Hyper-Threading/SMT is still very beneficial, even from a power efficiency perspective. It could be argued that AMD’s architecture probably benefits more from multithreading than Intel’s competing architectures. Nevertheless, AMD’s Zen 5 architecture shows that multithreading is beneficial if optimized.
It’ll be engaging to see how AMD’s Ryzen AI 300-series processors stack up against Intel’s Lunar Lake competition in the future. We won’t have to wait long for comparisons; Lunar Lake is due out next month.
