Raspberry Pi CM5 is a faster, drop-in upgrade

Original Article ↗ Hacker News Discussion ↗

Raspberry Pi’s new Compute Module 5 is seen as a substantial, mostly drop-in performance upgrade over the CM4, bringing 2–3x faster CPU, USB 3, and better I/O while retaining the broader Pi software ecosystem and long-term availability guarantees. Commenters weigh its value against x86 mini-PCs and Rockchip-based CM alternatives for use in NAS boxes, Home Assistant hubs, synthesizers, and commercial products, noting that Pi’s strong community support and maintained kernel fork often outweigh raw specs. Concerns center on storage performance with SD cards, the lack of modern hardware video encoders, connector reliability in products, and pricing that now competes more directly with low-end Intel/AMD systems.

Carrier Boards, NAS, and Hardware Choices

  • Multiple suggestions for CM-based NAS carrier boards: Axzez Interceptor and Radxa Taco (though Taco availability and heat/power efficiency are concerns).
  • Some users prefer skipping SBC NAS entirely in favor of small x86 boxes (ThinkCentre Tiny, N100/N150 ITX boards) plus external enclosures, citing better power and less cabling chaos.
  • USB3 multi-bay HDD enclosures are debated: some warn they’re “bad,” others report years of trouble‑free ZFS use with cheap 4‑bay boxes.
  • PCIe in small PCs can be repurposed (e.g., for extra NICs or storage), but often requires proprietary risers and sacrifices internal bays.

Pi CM in Commercial Products & Suitability

  • Compute Modules appear in commercial devices (synths, music gear, 3D printers). Many run customized Linux with userland UI on top.
  • Opinions split on using CM4/CM5 in products:
    • Pro: Long availability (8–12 years), combined volume lowers component cost, good software stack, modular FCC compliance saves certification money.
    • Con: Scarcity during shortages burned some teams; one user refuses to use Pis in retail products again. Connector reliability vs soldered SoM is a concern for some.
    • Guidance: CM is reasonable up to roughly 10k/year volumes; above that, custom designs may become cost‑effective.

Kernel, Ecosystem, and Support

  • Pi’s kernel is a maintained fork of mainline Linux; patches are regularly upstreamed and tracked near current versions.
  • Some value Pi for strong community support and relatively smooth mainline compatibility vs other ARM boards.
  • Others complain that non-Pi distros can still be painful, and that running truly vanilla kernels with fully open drivers remains a goal rather than reality.

Performance, I/O, and Boot

  • Users note large real‑world speed gains from CM5 and Pi 5, especially USB3 and PCIe vs older models.
  • Boot time of ~23 seconds is seen as improvable via trimming systemd units or using lightweight images.
  • SD card I/O on Pi 4 is widely criticized. A2‑class cards and especially USB3 SSDs are reported to dramatically improve responsiveness.
  • Suggestions include preload, F2FS, and tuning/overclocking SD bus, but external SSDs are generally considered the real fix.

Video Encode/Decode Changes

  • CM5’s SoC provides hardware H.265 decode but no hardware encode; encoding is CPU‑only.
  • Some argue Pi 5 CPU improvements can outperform Pi 4’s hardware encoder in speed/quality if power isn’t constrained.
  • Others see this as a regression for low‑power or dedicated encode use cases.

Alternative SoMs and Boards (Radxa, Rockchip, OrangePi)

  • Radxa CM5 with RK3588S2 is mentioned as significantly faster than Pi CM5 at slightly higher price and offering an NPU useful for ML/LLM workloads.
  • Trade‑off emphasized: better raw specs vs weaker ecosystem and support.
  • Other Rockchip/OrangePi boards can outperform Pi 5 in CPU, RAM, and accelerators, but users report kernel, driver, and long‑term support as “barely there” or fragile.

Home Assistant Yellow and CM5/Alternatives

  • CM5 support for Home Assistant Yellow has been announced.
  • Interest in running Yellow with Radxa CM5 and mainline kernels exists, but no clear success reports; compatibility is described as uncertain and risky for a live home setup.

Form Factor, Pricing, and Use Cases

  • Debate over “credit-card sized” marketing; dimensions match roughly in two axes, but thickness makes “volume” comparison pedantic.
  • Some feel Pi pricing has drifted into low‑end x86 territory; others counter that Pi’s value is more in support than raw specs.
  • The original $5 Zero is remembered as effectively unavailable; Zero 2W at $15 is seen as more usable but no longer in “impulse buy” territory.
  • CM5 performance is compared to decade‑old laptop CPUs; people are surprised there isn’t a popular CM‑based upgradable laptop shell, but note it’s hard to beat used x86 laptops.