Why do my USB ports turn on whenever I plug something into the ext. lead?

[freshgum bubbles]

So... let's set the scene: the computer is turned off (although still connected to mains). USB sockets don't have 5V going through them anymore.

Now, when I turn on something like my speakers (which are on the same extension lead), all of a sudden the USB ports have 5V going through them?!?!

I managed to reproduce this a couple of times (and last year), although it doesn't do it after around 5 times.

Is this a known issue with Strix Z270F / standard EVGA 500W PSU?

[Eighjan]

29 minutes ago, freshgum bubbles said:

So... let's set the scene: the computer is turned off (although still connected to mains). USB sockets don't have 5V going through them anymore.

Now, when I turn on something like my speakers (which are on the same extension lead), all of a sudden the USB ports have 5V going through them?!?!

I managed to reproduce this a couple of times (and last year), although it doesn't do it after around 5 times.

Is this a known issue with Strix Z270F / standard EVGA 500W PSU?

How are the speakers connected to the PC's base unit?

Is the PC switched off or 'Hibernating'?  If the latter, powering the speakers on could send a signal to the motherboard & wake it up.

 

My PC has the based unit switched on, 24/7 & all I power off is the speakers & monitor...

Might be worth checking to see if any of the motherboards utilities/bundled software - that control power - are installed & overriding how you want the system to behave.