This document describes the integration of two Raspberry Pi Compute Module based systems within a single FIVE Wood mini-ITX tower case. The system consists of a RISC OS FAST SATA machine based on the Compute Module 4 (CM4) and a Linux-based system using Compute Module 5 (CM5). As the enclosure was originally designed for a standard mini-ITX motherboard, mechanical and electrical modifications were required. A custom 3D-printed internal frame was designed to support both systems and internal storage case for the 2.5" SATA drives for the RISC OS FAST machine. The storage case is a sliding design allows easy installation and removal.
Internal power supply (PSU) is used to power the both systems.
For this project I'm using a beautiful FIVE Wood Case mini ITX tower from RISCOOSbits that I bought when I visited the RISC OS London Show 2025.
A custom 3D-printed internal frame was designed to fit within the mini-ITX tower. The frame provides mounting points for both CM4 and CM5 IO boards, structural support for the upper board, and an integrated sliding case capable of housing up to four 2.5-inch SATA drives. The sliding design allows easy installation and removal.
3D printed frame fitted into the tower and bolted to the left side of the case with four M3x10mm screws.
3D printed support to carry the uper mainboard fitted on top of the CM5 board and bolted to the frame with M2.5x15 screw.
The CM4-based RISC OS FAST machine is equipped with a PCIe-to-SATA expansion card, allowing connection of up to four SATA drives. These drives are mounted within the 3D-printed SATA case. The Linux system includes an internal NVMe drive mounted to the CM5 board.
All ports from both Compute Module IO boards are accessible from the rear of the enclosure. The rear panel includes the PSU main power switch, an external antenna connector for the CM5, optional antenna for the CM4, and a reset button for the CM4 board. The CM4 board is connected to the PCU internaly using Floppy Drive Connector to but the CM5 receives power through a rear USB-C connection from the main PSU with special cable, MOLEX to USB-C.
The power supply is ARGUS SFX-300W 82+. ON/OFF switch on front of the case turn on and off the PCU by connecting PS_ON# pin to ground.
The FIVE Wood case is very packed when the PSU has been fitted, I recommend EIGHT Wood case if using internal PSU.
The RISC OS FAST machine is running 10°C colder than before. The PSU fan is blowing the air to the main boards. It is nocieless and rotate very slow but enough to cool both systems.
To develop this further I need to add a power and reset buttons for the CM5 board and USB port in the front panel, I'm uisng the two front USB ports for the FAST machine.