AMD's Strix Point: Zen 5 Hits Mobile

Original Article ↗ Hacker News Discussion ↗

Perf/Watt and Battery Life Comparisons

  • Strix Point / Ryzen AI 9 HX370 is seen as a major step for x86 mobile: in some reviews its battery life comes within ~1–2 hours of M3 MacBook Pro and Qualcomm Snapdragon X Elite machines.
  • Disagreement over how efficient it really is:
    • Some cite Cinebench/Notebookcheck data showing M3 (and Snapdragon X Elite) with clearly higher perf/watt, especially in single-threaded loads.
    • Others argue those reviews often use wall-power (including dGPU, screen, etc.) or vendor‑boosted TDPs (e.g., 80 W) that exaggerate x86’s inefficiency; CPU‑only measurements around 30–33 W make HX370 look much closer.
  • Several note that vendors often push laptop CPUs to high power points to win benchmarks, sacrificing efficiency; at ~15–30 W, recent Ryzen parts can be very efficient.
  • Battery life also depends heavily on OEM design (battery size, display, dGPU, firmware, OS power management), not just CPU.

ARM vs x86 Efficiency and ISA Debate

  • One camp: ARM (esp. Apple and Qualcomm designs) is inherently more efficient; they highlight large ST perf/watt gaps (e.g., M3 being multiple times more efficient than Zen 5 in Cinebench R24 ST).
  • Counter‑camp: ISA and x86 decoding overhead contribute only a small share of total power; most of the gap comes from process node, microarchitecture, and whole‑stack optimization.
  • Long subthread on:
    • Decoder complexity, micro‑op caches, instruction length and code density (x86 vs ARM64 vs RISC‑V).
    • Memory models and atomics (TSO on x86 vs weaker models on ARM).
    • Conclusion is mixed: ISA quirks do matter, but they don’t fully explain observed gaps.

Benchmarks and Methodology Disputes

  • Cinebench R23 is criticized as biased toward x86 (Intel Embree AVX code, weak NEON usage); R24 and Geekbench 6 are preferred for cross‑ISA comparisons.
  • Some argue Cinebench (especially ST) is an odd proxy for “real‑world” single‑thread performance; others defend it as realistic for rendering workloads.
  • There’s broad agreement that perf/watt must be compared at the same power point; raw “points per watt” without context can be misleading.

Laptop Design, Fans, and User Experience

  • Multiple comments argue that OS‑level controls (fan‑speed or max‑power sliders) would better align user preferences (quiet vs peak performance) with OEM tuning.
  • Thin, fanless designs (MacBook Air‑class) are highly valued by some; others prefer thicker, actively cooled laptops and are willing to tolerate fan noise.
  • Many note that idle and low‑load efficiency plus proper platform power management (BIOS, drivers, discrete GPU power‑gating) dominate perceived battery life.

Products, Form Factors, and NPUs

  • Interest in Zen 5 mini‑PCs and the upcoming Strix Halo (more cores, bigger iGPU, higher bandwidth) for console‑like small systems.
  • Questions about always‑on NPUs: some doubt typical software will exploit them and resent paying silicon area for features they may never use.