How to Keep USB Power On While the PC Is Off - OneSDR

Many users want their USB devices, such as charging phones, powering LED lights, fan (shown below) or running peripherals, to stay powered even when their PC is turned off.

A USB Fan

This functionality can be achieved on most modern motherboards, as they include options to supply USB power even when the system is shut down.

This guide walks you through the steps to enable USB power while your PC is off.

Table of Contents

Why Keep USB Power On?

Keeping USB power on when the PC is off can be useful for several reasons:

Charging Devices: Charge smartphones, tablets, or other gadgets through USB ports.
Powering USB Devices: Operate peripherals like keyboards, mice with lighting, or external hard drives.
Convenience: Avoid using a separate power source for USB-powered devices.

Steps to Enable USB Power While PC Is Off

Check Your Motherboard’s Specifications

Modern motherboards often include an option to keep USB power on in their BIOS or UEFI settings. Look for a feature like ErP, EuP, or USB Standby Power in your motherboard manual.

Access the BIOS/UEFI Settings

To configure USB power:

Restart your computer.
Enter the BIOS/UEFI by pressing the designated key during startup (commonly DEL, F2, or F12).

Locate USB Power Settings

Look for settings related to USB power or standby power. These options are typically found under:

Power Management
Advanced
USB Configuration

Disable ErP/EuP

The ErP (Energy-related Products) or EuP (Energy-using Products) setting, when enabled, turns off USB power when the PC is off to save energy. To keep USB power on:

Locate the ErP/EuP option in BIOS.
Set it to Disabled.

Enable USB Standby Power

Some motherboards have a dedicated option like USB Standby Power or USB Power in S5 (S5 is the shutdown state). Enable this option to allow USB power delivery when the PC is off.

Save and Exit BIOS

Press the appropriate key (usually F10) to save your changes and exit BIOS/UEFI. Your system will reboot, and the USB ports should now remain powered even when the PC is off.

For Specific Motherboards

MSI: Disable “ERP-ready” and enable “Resume by USB device” in “Wakeup event setup”
Gigabyte: Disable “ERP Ready”
ASUS: Disable “ERP Ready” and enable “Asmedia USB 3.1 Battery Charging Support” or “USB Power delivery in soft state (s5)”
AsRock: Disable “Deep Sleep” in ACPI Configuration

Windows Device Manager

Open Device Manager (right-click Start menu and select “Device Manager”).
Expand “Universal Serial Bus controllers”.
Right-click each USB hub and select “Properties”.
In the “Power Management” tab, uncheck “Allow the computer to turn off this device to save power”.

Power Options

Open Control Panel > Power Options.
Click “Change plan settings” for your current power plan.
Click “Change advanced power settings”.
Expand “USB settings” > “USB selective suspend setting”.
Set both “On battery” and “Plugged in” to “Disabled”.

Alternative Methods

Use Powered USB Hubs

A powered USB hub is an external device with its own power adapter. These hubs provide constant USB power, regardless of the PC’s state.

Check Rear USB Ports

Some motherboards have specific rear USB ports that remain powered even when the PC is off. Look for ports labeled as Charging or Always On in your motherboard documentation.

Enable Wake-on-USB

If you want to use USB devices to wake your PC while keeping them powered:

Go to the Device Manager in Windows.
Expand Universal Serial Bus controllers.
Right-click your USB root hub and select Properties.
Under the Power Management tab, check Allow this device to wake the computer.

Limitations and Considerations

Power Consumption: Keeping USB power on while the PC is off can slightly increase energy usage.
Motherboard Support: Not all motherboards support keeping USB power on while the system is shut down.
Device Compatibility: Some devices may not work properly with low standby power.

Summary

Keeping USB power on while your PC is off is a convenient feature for charging devices or powering peripherals. By adjusting your BIOS settings, disabling ErP/EuP, or using powered USB hubs, you can ensure your USB ports stay powered even when the computer is shut down.