While searching for a solution to an external hard drive's LED continuing to blink after shutting down the system, I came across the 'ErP Enabled' setting in my BIOS.

I've set ErP to "Enabled (S4+S5)" with the available options being disabled, S4+S5 and S5. Everything seems to be working fine and the external hard drive's LED no longer blinks after shutting down the system.

So I can't help but wonder: Is there any reason not to enable ErP on a capable system that does not need to power USB devices while it is powered off?


1 Answer 1


You may want to wake up your computer from your keyboard or your mouse.
Or you may want to charge your cell phone on one of your computer USB ports.
In this case, those USB devices need to be powered, otherwise it's safe to power off your USB ports.

  • 1
    Probably not enough current will be provided for charging the phone. The Erp setting allows 1 Watt for mice, keyboards and other low-power devices. May 29, 2018 at 18:54

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