Newly-Released Raspberry Pi 4 USB 3.0 Firmware Drops Power Draw, Heat Output on All Models

The hot-running Raspberry Pi 4 now has a new firmware which tames its heat output a smidge by enabling power saving on the Via Labs VL805 USB 3.0 host controller chip — after developers fixed a flaw in an earlier build of the firmware which could cause selected USB 3.0 devices to perform incredibly slowly.

The Raspberry Pi 4 single-board computer is an impressive beast, with up to 4GB of RAM hanging off a quad-core 64-bit Arm Cortex-A72 CPU and shiny new Broadcom VideoCore VI GPU inside Broadcom's custom-designed BCM2711B0 system-on-chip. Its power, however, comes at a price: As well as drawing more power than any of its predecessors, the board generates considerably more heat - enough, in fact, to hit the processor's thermal throttle point and pull down its performance.

Since its launch, the engineers at the Raspberry Pi Foundation have been working on optimising it in a variety of ways. Earlier this year an updated firmware for the VL805 USB 3.0 controller was released for beta testing, promising to drop the power draw and thus heat output — only to be pulled back in for more work when it was found to cause selected USB 3.0 devices' throughput to drop from megabytes to kilobytes per second.

The bugs in the firmware are now fixed, however, and the revised version is ready to be installed. Those already running Raspbian can install the new firmware quickly and easily using the apt package manager:

sudo apt update && sudo apt upgrade && sudo apt install rpi-eeprom rpi-eeprom-images

Once the two key packages - rpi-eeprom and rpi-eeprom-update - are installed, reboot the Raspberry Pi 4 to upgrade the firmware. The installation can be verified with:

sudo rpi-eeprom-update

If you see VL805 firmware version 000137ab, you're successfully updated — and it's worth doing, as testing reveals a rough 0.4W idle and 0.3W load reduction in power draw, even without USB 3.0 peripherals connected. Less power means a cooler board, with those figures resulting in a drop of 5.2°C in temperature measured at the VL805 IC itself and 2.6°C measured at the SoC.

UPDATE: The Raspberry Pi Foundation has confirmed that this week's release also includes a range of other platform enhancements which improve efficiency elsewhere, including within the SoC itself. Taken all together, these should lead to an even higher reduction in power draw and operating temperature than indicated by the above, VL805-focused test results.