Photos: What is the Raspberry Pi 4 Model B? A closer look at the new board and what it can do

Same size, different layout

As you can see, while the Raspberry Pi 4 Model B, on the left, is the same size as the Raspberry Pi 3 Model B+, it has a different layout.

The change has been necessary to incorporate the dual micro-HMDI ports on the board.

The new layout means side panels in cases for older Pi boards won't fit correctly. I also found the board overheated when playing video while using an older case, with the computer throttling performance to reduce temperature.

SEE: Raspberry Pi 4 Model B review: This board can really replace your PC

On the back

The underside of the Pi 4 is more bare than previous boards, housing only the microSD card reader. 

SEE: Raspberry Pi 4 Model B review: This board can really replace your PC

The CPU

The Raspberry Pi 4 runs on a Broadcom BCM2711, a new SoC which sports a quad-core Arm Cortex A72-based processor, running at 1.5GHz -- a more modern and slightly faster CPU than the quad-core Arm Cortex A53-based CPU in earlier boards. The VideoCore 6 GPU should be able to playback 4K@60FPS H.265-encoded video.

The memory chip is now on top of the board, with the Pi 4 offering up to 4GB of LPDDR4 RAM -- considerably faster than the LPDDR2 RAM found on earlier Pi boards

The newer, faster RAM available on the Pi 4 makes a considerable difference to how comfortable the machine feels to use as a desktop computer -- particularly when browsing the web -- and with dual-display support is a good fit for budding developers looking for a cheap machine.

Wi-Fi and Bluetooth

Wireless connectivity is similar to the Pi 3 B+, with the Raspberry Pi 4 offering dual-band 802.11ac Wi-Fi, but Bluetooth is upgraded to 5.0, compared to the Bluetooth 4.2 found in the Pi 3 B+.

Dual-screen support

The board can be used with two monitors at once via its dual micro-HDMI ports. These are able to support up to twin 4K@30Hz screens or a single 4K@60Hz monitor. 

As with previous boards, the Pi 4 also includes a 4 pole stereo audio output and composite video jack.

USB 3.0 arrives

The Pi gets faster ports for hooking up storage and other peripherals, with 2 x USB 3.0 and 2 x USB 2.0 ports.

The position of the USB and Ethernet ports has changed, with the USB ports now to the left of the Ethernet.

Better hardware support

Like the Pi 3 B+, the Pi 4 also sports a 40-pin, general purpose input-output (GPIO) header for hooking up other boards, sensors, motors, and homemade hardware to the Pi.

The pin layout is identical to earlier versions of the Raspberry Pi and the Pi 4 should be compatible with many hardware add-ons for earlier boards. 

The Pi 4's GPIO header also supports more connections, with UART, SPI and I2C interfaces each supported on four additional pins, and with fixed support for clock stretching over I2C interfaces.

True Gigabit Ethernet

Like the Pi 3 B+, the Pi 4 has a Gigabit Ethernet port, however, unlike the previous board, the Pi 4 offers true Gigabit Ethernet speeds due to not being constrained by a shared USB 2.0 bus.

More display options

Useful for hooking up small LCD screens to the Pi, the usual DSI connector found on Pi boards is also present.

USB-C power

The Pi 4 is the first board to use USB-C for its power, and requires a 5V/3A power supply, giving the Pi 4 an extra half amp power compared to earlier boards.