A palm-size IO board for Raspberry Pi CM5 — my hands-on review and tests | CM5 Minima From Seeed Studio

If you’re playing with the Raspberry Pi Compute Module 5 (CM5), you know the official dev board is huge. For a couple of my projects I wanted something tiny—something I could tuck behind a display or drop into a small enclosure. That’s where this small CM5 Minima IO board from Seeed Studio came into my workflow. It literally fits in my palm, but it still exposes the bits I care about.

What this little board packs

Despite the footprint, it’s a surprisingly complete breakout:

• M.2 M-key slot for 2230/2240 NVMe drives (PCIe x1).
• Gigabit Ethernet (RJ45).
• Two USB-C ports: one for PD power and one USB 2.0 data/OTG.
• Full-size HDMI (4K@60).
• DSI/CSI combo connector.
• SPI header, CPU fan connector, RTC battery header.
• Power button, power/activity LEDs.
• CM5 connectors and a boot/flash switch (run OS vs. eMMC flashing).
• Open-source hardware design (co-created with a GitHub contributor), which I always appreciate when I’m building around a board.

First setup: fan, CM5, NVMe

I started by mounting a small fan on my CM5, dropped the module onto the board, and plugged the fan into the dedicated header. Then I slid in a 2242 NVMe just to see how storage would behave on a single PCIe lane.

Flashing the OS to eMMC (quick notes)

Flashing was straightforward:

1. Flip the boot switch to the nRPIBOOT position.
2. Connect the USB cable to my host machine.
3. Run the rpiboot command to make the emmc storage avaialble as mass storage and flash the image to eMMC.
4. Flip the switch back to Run and power-cycle.

If you’re new to this, the switch is the key—wrong position and the eMMC won’t present over USB.

Here is a detailed guide to flash an OS on the eMMC storage on the Raspberry Pi Compute Module 5.

Storage & networking performance

NVMe: After confirming the drive was detected, I bumped the PCIe link to Gen 3 in the config. With a single lane, I saw roughly ~864 MB/s, which is right in line with PCIe Gen3 x1 expectations for a decent 2230/2240 drive.

Ethernet: The gigabit port behaved as it should—around ~940 Mb/s in my tests.

Thermals & the fan kick off Out of the box, the fan kicked in once the CM5 crossed ~50 °C (default threshold). Under light loads the board stayed quiet; under sustained builds the fan spun up predictably and kept temps from creeping.

USB-C behavior

The power port negotiated fine with my PD bricks. The data port enumerated my USB 3.x device as Gen 2 capable (10 Gb/s class), which is what I expect here. For my use, plugging in a fast external SSD for quick copies felt snappy.

Trying a Compute Module 4

Curiosity got the better of me, so I tried a CM4 on this board. A couple of observations:

• With a PD power supply, the CM4 didn’t start. Swapping to a regular USB power supply brought it to life.
• NVMe didn’t show up, and the USB-C (data) port wasn’t working for me.
• Ethernet and HDMI did work.

Bottom line: you can make it talk over Ethernet (and even get HDMI out), but this board isn’t officially aimed at CM4, and the missing NVMe/USB makes it a limited fit unless you’re happy running headless over Ethernet or with basic HDMI output only.

What I like (and what to watch)

Likes

• Tiny footprint with the right mix: NVMe, Ethernet, HDMI, and USB-C.
• Sensible fan header and default thermal behavior.
• Open-source design—handy if you need to audit or adapt.

Watch-outs

• Single PCIe lane is expected on CM5, so NVMe tops out around ~900 MB/s—great for apps and logs, just don’t expect desktop-class Gen4 speeds.
• The CM4 experiment is quirky (power/PD, missing NVMe/USB); I treat CM4 support as “nice if it happens,” not a guarantee.
• Availability can be spotty. Pricing for me was about $65, and at the time it was on back-order with plans for EU/US warehouse stock.

Where this board fits in my builds

Anywhere I need a compact CM5 brain with real storage and 4K60 HDMI: kiosk displays, edge nodes with local caching, instrument controllers in tight spaces—this board slides in without forcing a giant carrier.