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Raspberry Pi 5 has a single-lane PCIe 2.0 interface on a 16-pin FFC connector, while HAT+ is a separate specification for add-on boards that connect through the Pi’s 40-pin header. The distinction matters: PCIe describes an electrical interface; HAT+ defines how an add-on board identifies itself and behaves as a Raspberry Pi accessory.
What the Raspberry Pi 5 PCIe port provides
The Pi 5 exposes one PCIe lane through a 16-pin, 0.5 mm-pitch flat-flex cable (FFC) connector. Raspberry Pi documents PCIe Gen 2.0 at 5 GT/s as the default. Gen 3.0 is not certified and may be unstable, so it should be treated as an experiment, not a supported way to obtain a guaranteed speed increase. Raspberry Pi’s hardware documentation describes the interface and its operating mode.
The connector carries PCIe transmit and receive signals, clock, reset, and sideband signals used for functions such as clock requests, power enable, and device detection or wake. Raspberry Pi’s connector specification limits the FFC cable to 50 mm and requires controlled impedance. A generic ribbon cable that merely fits is not necessarily suitable for reliable PCIe signaling. The PCIe connector specification is intended for hardware design; compliance with the connector details does not by itself guarantee that any particular peripheral will work with the available software or power.
The connector specification assigns 5V to two pins, each rated at 500 mA. That is a rating for the Pi connector’s supply pins; it is not the same as the downstream power capability of an adapter with its own power circuitry. For example, the official M.2 HAT+ brief specifies that its adapter can supply up to 3A to connected M.2 devices. Raspberry Pi’s connector specification and the M.2 HAT+ product brief describe these different figures.
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- High-Speed NVMe SSD Support --- The HAT board supports M.2 NVMe SSDs for fast data access and storage.
- M.2 Interface --- Utilizes the PCIe interface for high-performance communication between the SSD and Raspberry Pi.
- Power over Ethernet (PoE+) Capability --- Streamlines the power supply setup by allowing the Raspberry Pi 5 to be powered through the Ethernet port.
- 5.1V/4.5A Output --- Ensures that the Raspberry Pi 5 and any connected peripherals receive adequate power for optimal performance.
- Active Cooler --- Pi5 Active Cooler combines an aluminium heatsink with a PWM fan to keep your Raspberry Pi 5 maintain optimal operating temperatures, ensuring reliable performance for various applications.
What HAT+ means—and what it does not
HAT+ is Raspberry Pi’s updated specification for add-on boards mounted on a Raspberry Pi and connected to its 40-pin header. The original HAT specification is deprecated; new HATs are expected to follow HAT+. A PCIe accessory does not automatically become a HAT+: it can use the PCIe port without meeting the HAT+ rules, and it may still be used as an add-on board without claiming the HAT+ designation.
The HAT+ specification covers board behavior and identification, not just connector fit. Changes include required compatibility with the Pi’s STANDBY power state, simpler ID EEPROM contents, less prescriptive physical dimensions, and defined classes for stackable and power HAT+s. The EEPROM carries identity information such as a product UUID, vendor string, and product description; firmware reads it at boot.
Rank #2
- Compatibility: Pi 5 PCIe M.2 HAT only compatible with Raspberry Pi 5 2GB/4GB/8GB/16GB SBC (NOT include Raspberry Pi 5), NVMe base for Raspberry Pi 5, Model: X1001, the matching case is P579
- M2 Key-M NVMe SSD Supported: Support M.2 KEY-M NVMe SSD 2230/2242/2260/2280 length installation; Comes with SSD copper pillar for 2230/2242/2260 SSD installation
- User Manual and FAQ: Google Geekworm WiKi and search X1001 and its FAQ; Refer to the FAQ to do troubleshoot step by step if can't boot/recognize from NVMe SSD
- Designed as a basic PCIe expansion board for the Raspberry Pi 5, the X1001 features limited standalone hardware functionality and requires proper OS configuration, stable FFC cable connection, and compatibility between firmware and SSDs for reliable operation.
- Power Supply Requirements: The X1001 is powered directly through the PCIe FFC ribbon cable. For stable operation, use the Raspberry Pi 5 PD 27W USB-C Power Supply (5.1V/5A). Note: Standard phone chargers may not provide sufficient power for NVMe SSDs, which can result in SSD instability, data corruption or drive failure.
That recognition is not universal driver support. The firmware can identify a board and load a named Device Tree overlay, but the overlay and operating-system software still need to provide the relevant pin configuration and driver information. A board’s compliance and its practical software support are related, separate questions. The official specification states: “Only boards that follow the HAT+ specification can be marketed as HAT+ boards.” Read the HAT+ specification for the complete requirements.
Using the PCIe port for an NVMe drive
Raspberry Pi’s official M.2 HAT+ adapters provide a straightforward example of the port’s purpose: they connect an M.2 M-key device to the Pi 5’s single-lane PCIe 2.0 interface. Raspberry Pi’s product brief states a peak transfer rate of 500 MB/s and supply capability of up to 3A to connected M.2 devices. The 500 MB/s figure is a stated peak interface rate, not a promise of realized disk speed; actual storage performance depends on the drive and system conditions. See the M.2 HAT+ product brief.
Rank #3
- Standard Raspberry Pi 40PIN GPIO header, supports Raspberry Pi 5
- PoE (Power Over Ethernet) capability，IEEE 802.3af/at-compliant
- Fully isolated switched-mode power supply (SMPS)
- Onboard high speed active cooling fan, with metal heatsink, better heat dissipation
- Provide e-user manual, please check the manual carefully before using!
The two official variants differ in supported drive length and physical clearance:
| Adapter | Supported M.2 lengths | Cooling and case fit |
|---|---|---|
| M.2 HAT+ | M-key 2230 and 2242 | Can fit with the Active Cooler underneath. Does not fit inside the Pi 5 case with its lid and fan in place. |
| M.2 HAT+ Compact | M-key 2230 only | Designed around the Pi 5 case fan. Cannot fit with the Active Cooler beneath it. |
Both variants use single-lane PCIe 2.0 and have the same stated peak interface transfer rate and M.2 power capability. Check drive keying and length, the case, and the intended cooling arrangement before choosing an adapter; the right option is determined by physical fit as well as drive format. Raspberry Pi’s product brief gives the supported lengths and clearance notes.
Rank #4
- [All-in-One Audio & Display Expansion] Elevate your Raspberry Pi projects with the Whisplay HAT. It seamlessly integrates a high-performance audio codec, an onboard speaker, dual microphones, and a vibrant 1.69-inch color LCD (240x280 resolution) into a single, compact board. Perfect for building smart speakers, voice assistants, and creative media terminals.
- [Perfect Match for Pi Zero & More] Designed with the exact same form factor (65mm x 30mm) as the Raspberry Pi Zero and Zero 2 W, this expansion board fits flawlessly into handheld and ultra-portable setups. It is also fully compatible with Raspberry Pi 5 via the standard 40-pin GPIO header.
- [High-Fidelity Audio System ] Powered by an integrated high-quality audio codec with dual microphones and onboard speaker for accurate voice capture, and a PH2.0 expansion interface for external speaker connection—ideal for voice recognition, AI chatbots, and high-quality audio playback.
- [Developer Friendly & Programmable] Equipped with programmable physical buttons to trigger scripts or custom functions, RGB LEDs add visual appeal and status cues to your projects. Comes with full Python drivers, open-source documentation, and ready-to-run GitHub examples to kickstart your next AI or IoT project.
- [Zero Soldering, Easy Installation] Simply plug the Whisplay HAT directly onto your Pi's 40-pin GPIO pins and start creating. Note: Please handle by the edges of the PCB to avoid pressing or putting heavy pressure on the fragile glass screen.
Enabling PCIe in Raspberry Pi OS
PCIe is off by default unless a HAT+ is connected, according to Raspberry Pi’s computer documentation. For a non-HAT+ PCIe device, the documented method is to enable the interface in the boot configuration and restart:
- Open
/boot/firmware/config.txton Raspberry Pi OS. - Add
dtparam=pciex1on its own line. - Save the file and reboot the Raspberry Pi.
PCIe boot is a separate setting and is also disabled by default. If the goal is to boot from a PCIe storage device, update the bootloader configuration; for a non-HAT+ device, Raspberry Pi documents adding PCIE_PROBE=1. Consult the current Raspberry Pi PCIe device documentation for the applicable bootloader procedure, since software instructions can change.
Best Value
- Aluminum case is designed for P33 M.2 NVME M-Key PoE+ Hat. It can access to most of ports of Raspberry Pi Board.
- High-Speed NVMe SSD Support --- The HAT board supports M.2 NVMe SSDs for fast data access and storage.
- M.2 Interface --- Utilizes the PCIe interface for high-performance communication between the SSD and Raspberry Pi.
- Power over Ethernet (PoE+) Capability --- Streamlines the power supply setup by allowing the Raspberry Pi 5 to be powered through the Ethernet port.
- 5.1V/4.5A Output --- Ensures that the Raspberry Pi 5 and any connected peripherals receive adequate power for optimal performance.
Designing a PCIe accessory or a HAT+
For a custom PCIe board, follow the connector specification rather than relying on physical compatibility alone. It defines the 16-pin interface, single-lane signaling, sideband connections, controlled-impedance requirements, cable limit, and connector supply-pin rating. Board-level power conversion and the peripheral’s needs must be designed separately.
If the board is also intended to qualify as a HAT+, design to the HAT+ specification in addition to the electrical requirements of the interface it uses. That means addressing the 40-pin add-on-board connection, STANDBY compatibility, ID EEPROM requirements, and the specification’s rules for identifying and marketing a HAT+. Raspberry Pi’s hardware leader James Adams described the motivation for the update in Raspberry Pi Official Magazine: “The original HAT specification was written back in 2014, so it is now very overdue for an update.”
Other HAT+ examples
PCIe storage is not the only use of the HAT+ ecosystem. Raspberry Pi’s documentation lists AI HAT+ models in 13 TOPS and 26 TOPS variants, as well as AI HAT+ 2 at 40 TOPS, which adds support for local large language models and vision-language models. These are separate product examples; their capabilities do not change what the Pi 5 PCIe connector or the HAT+ standard guarantees. Raspberry Pi’s AI HAT+ documentation provides product details.
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