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I've built a new pc and it works fine but I have this strange "problem" that about 1 out of 5 times i suspend or shutdown it, the backlight of the keyboard and/or rgb on the mouse stays on. When I wake/turn back on the pc everything works as expected, no errors or any info in the event log.

I'm on windows 10, using two usb2's motherboard ports, same mouse and keyboard had no problems in my old build. I've tried playing with the various usb related power options, no luck. Could this be a software thing? Or maybe BIOS? or even worse, hardware issue?

EDIT I've done more tests:

  • tried another PSU
  • tried every possible windows settings related to USB suspension
  • unplugged every not-essential peripheral
  • the only BIOS setting that has an effect is ErP set to enabled, but it only works for shutdown, not standby, and also doesn't really fix the issue, it just "covers" it because you can still see the device on when the rest is off for few seconds before ErP cuts the power
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  • The USB is using 5V from the Power Supply (PSU).
  • Motherboard doesn't cut off the power to a legacy USB port or on the back.
  • BIOS is still turn off if no power on the motherboard and it needs to turn on with 5V, 3.3V, and 12V simultaneously.
  • Software wouldn't magically turn on if the hardware turns off.

So the main problem is your PSU, it could be the flyback from PSU still storing the energy and delayed-release when the capacitor on the output is empty. Making it like your computer turn on, but is it not. Maybe the 5V line from your PSU has faulty.

Try to unload your PSU, turn it on manually (check google how to turn on your PSU), check the voltage of your 5V (see google again) with a voltmeter or multitester. Turn off the PSU, and let's see 5 minutes with your voltmeter still connected to it. If it jumped on reading 5V then your PSU is faulty go to guarentee it.

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  • Thanks, I'll get a voltmeter and test it, but there's something I don't understand. If the PSU is still delivering power shouldn't both mouse and keyboard be on all the times? It seams to me that each port has a 1/5 chance independently of the other, I've seen them both on but it's like 1/25 chance.
    – flagg19
    Commented Dec 27, 2020 at 11:08
  • it should be off or more precisely the PSU goes into deep sleep state. This is i don't know too, but before we are looking at the motherboard we should the PSU which is the main supply of voltage right?
    – Cubic273.15
    Commented Dec 27, 2020 at 11:26
  • tested the power supply, no issues found, also tried another older power supply, the problem persists :(
    – flagg19
    Commented Dec 31, 2020 at 15:05
  • @flagg19 can you post / photo the power management from your BIOS? it could be your BIOS setting is on suspended power, meaning is not fully turn off by specific BIOS setting
    – Cubic273.15
    Commented Dec 31, 2020 at 15:57

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