Search for single-board computers with a PCIe slot and you get vendor product pages. Almost nobody has written the comparison, which is odd, because "M.2 support" is the single most misleading phrase in SBC marketing. A Raspberry Pi 5 and a NanoPC-T6 both say it. One gives you a single lane of PCIe 2.0 through an adapter, the other gives you four lanes of PCIe 3.0 to a full-size slot. That is roughly an eight-fold difference in bandwidth behind identical wording.
Here is what the boards in our catalog actually expose.
Quick Picks
- Most PCIe bandwidth: FriendlyElec NanoPC-T6 — M.2 M-key PCIe 3.0 x4 plus a separate M.2 E-key, $109 to $139.
- Best value for four lanes: Radxa ROCK 5B — M.2 M-key PCIe 3.0 x4, from $59.
- Only true card slot: Zimaboard 832 — open-ended PCIe x4 slot, takes a real half-height card, $199.
- Cheapest M.2 board: Radxa ROCK 4C Plus — M.2 E-key, read the caveat below, $55 to $75.
- What not to assume: Raspberry Pi 5 (8GB) — PCIe 2.0 x1 via FFC and a HAT, $80.
Slot, Key and Lanes: The Three Things That Differ
Lanes and generation set the ceiling. One lane of PCIe 2.0 is about 500MB/s theoretical, roughly 450MB/s real after overhead. Four lanes of PCIe 3.0 is about 3,940MB/s theoretical. If you are building a NAS or running a fast NVMe drive, that gap is the entire decision.
Key decides what physically fits. An M.2 M-key slot takes an NVMe SSD. An M.2 E-key slot is for Wi-Fi and Bluetooth combo cards and is usually wired for fewer lanes. A board advertising "M.2" without saying which key has told you nothing useful.
Connector type decides how much of a build it is. A full-size M.2 slot soldered to the board takes a drive directly. An FFC ribbon connector needs a HAT, a cable and usually a case that accommodates both.
The Boards With Four Lanes
The Radxa ROCK 5B carries an M.2 M-key slot wired for PCIe 3.0 x4 off the RK3588, alongside 2.5GbE, 2x USB 3.0 and dual HDMI on a 100 x 72mm board. At $59 for 4GB and $79 for 8GB it is the cheapest genuine four-lane board here, and the reason it works as a compact NAS rather than just a dev board.
The FriendlyElec NanoPC-T6 has the same M.2 M-key PCIe 3.0 x4 slot for an NVMe 2280 drive, and then adds a second M.2 E-key slot carrying its Wi-Fi 6 module, so the storage slot stays free. Two 2.5GbE ports, an onboard RTC and a 12V barrel jack round it out for always-on server duty. 128 x 105mm, $109 to $139.
Between those two, the ROCK 5B is the value pick and the NanoPC-T6 is the one to buy if the box is a router, firewall or NAS where the second Ethernet port earns its price.
The Board With an Actual Card Slot
The Zimaboard 832 is the odd one out and the answer to a question the others cannot address. It has an open-ended PCIe x4 expansion slot, meaning a physical card edge, so a 10GbE NIC or a storage controller goes in directly rather than through an M.2 adapter. It also has two native SATA 3.0 ports off the chipset, not a USB-to-SATA bridge, and 32GB of eMMC.
The trade is the CPU. It runs an Intel Celeron N3450, quad-core bursting to 2.2GHz, with 8GB of LPDDR4, fanless at about 6W. Nobody is buying this for compute. They are buying it because x86 means TrueNAS SCALE, Plex transcoding and Windows all install without driver archaeology, and because native SATA plus a card slot is a NAS foundation no ARM board here matches. $199.
Read the Fine Print on the ROCK 4C Plus
The Radxa ROCK 4C Plus gets listed as a PCIe board and it needs a caveat. Its M.2 slot is E-key, intended for a Wi-Fi and Bluetooth combo card, with NVMe support only on select carrier revisions. It is a fine RK3399 board for GPIO projects at $55 to $75, with a Pi-compatible 85 x 56mm footprint and Gigabit Ethernet. It is not the board to buy for an NVMe build, and we would say the same to anyone who asked.
This is exactly the kind of thing the "M.2 support" phrasing hides.
What the Pi 5 Actually Gives You
The Raspberry Pi 5 exposes PCIe 2.0 x1 through an FFC connector. With an official or third-party HAT you get genuine NVMe boot, which is a real improvement over microSD in both speed and reliability, and for a media centre or a general project it is plenty. It is simply not in the same class as four lanes of Gen 3, and it costs you a HAT and a larger enclosure to get there.
Comparison Table
| Board | PCIe exposed | Connector | Extra storage I/O | Price |
|---|---|---|---|---|
| FriendlyElec NanoPC-T6 | PCIe 3.0 x4 | M.2 M-key 2280 + M.2 E-key | microSD, eMMC socket | $109 to $139 |
| Radxa ROCK 5B | PCIe 3.0 x4 | M.2 M-key | microSD, eMMC | $59 to $99 |
| Zimaboard 832 | PCIe x4 open-ended | Physical card slot | 2x SATA 3.0, M.2, 32GB eMMC | $199 |
| Radxa ROCK 4C Plus | M.2 E-key | M.2 E-key | microSD | $55 to $75 |
| Raspberry Pi 5 (8GB) | PCIe 2.0 x1 | FFC, HAT required | microSD | $80 |
Winner: Depends on the Card
For NVMe storage, the Radxa ROCK 5B is the pick. Four lanes of Gen 3 to an M.2 M-key slot from $59, and everything else on the board is competent.
For a NAS that needs a real expansion card or SATA drives, the Zimaboard 832 is the only board here that does it. The Celeron is slow and that is fine for a file server.
For an always-on box doing storage and networking together, the NanoPC-T6 is worth the extra $30 over the ROCK 5B for the second 2.5GbE port and the free E-key slot.
Related reading: Raspberry Pi 5 Alternatives covers the wider case for leaving the Pi platform, and Best Single-Board Computers with an NPU for AI Inference covers the same boards from the inference side. The full single-board computer catalog is filterable by storage interface.
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