The Raspberry Pi 5 requires a USB-C power supply that can offer the full 5V 5A that the board requires to offer full performance and current to connected devices.
Whilst the board will run on an older Raspberry Pi 4 power supply, there will be limitations to the current available to connected devices (USB).
We recommend customer pick up the new Raspberry Pi 27W USB-C power supply, as this can offer a stable 5V 5A for your Raspberry Pi 5 board.