Reader Bernie Holladay* writes:
Fred, I have a question about the USB-C port.
I needed to spec a USB connection for my new PC and choose Type-C. It was for a connection to a USB powered cooling pad for a laptop.
It worked fine but when I shut down I noticed the fans were still running and still were even when I disconnected the AC. Since they were still running my battery was being discharged. Not something I wanted to leave on.
I looked but could not find any way to control the power usage. Is there some setting I missed?
This might also be useful information if someone connected external hard drives to a USB-C hub.
Thanks, Bernie
That kind of always-on, pass-through power is an option available in many newer systems. The idea is that you can use your PC’s power supply (or battery) to power or recharge an external device at any time — even when the PC is otherwise off.
But it is usually an option, and can be controlled.
Many system vendors include an easy way to toggle pass-through power on or off. In some cases, it’s a setting in the UEFI/BIOS; in others there’s a separate app. For example, some Toshiba laptops come with a “Sleep and Charge” Utility. (Fig. 1.)
If your system doesn’t offer direct control, you usually can control it through Windows, by telling the OS whether or not to manage the USB root hub’s power:
- Open Device Manager (e.g. Type/say device manager in the Search/Cortana box).
- Right-click on the USB Root Hub whose port you wish to control; select Properties.
- On the Power Management tab, check or uncheck the box labeled Allow the computer to turn off this device to save power. (See Fig. 2.)
If checked/enabled, this setting tells Windows to actively manage the port’s power; Windows will de-power the port — preventing pass-through-power — when the PC is asleep or off.
If UNchecked/DISabled, Windows will leave the port’s power alone; if your PC’s hardware is otherwise set up for pass-through power, the port will then remain alive even when the PC is off.
Bernie, you want the former: If your PC doesn’t offer a utility to control the USB pass-through power, use the Device Manager method, and enable/check the box labelled ‘Allow the computer to turn off this device to save power.’ Your USB port should then be inert and unpowered when your PC shuts down.
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