I turn the surge-protected socket off when I close down my desktop PC. I've noticed for ages that when I turn the socket on the Ethernet port light on the router comes on even before powering up the PC. So PSU isn't completely controlled by the on/off power button at the front.

I've never known of any computer to 100% shutdown, must admit to have never tested the USB, but plug in a ethernet cable and the socket will light up, and a few weeks back I borrowed an old keyboard and mouse as my wireless adaptor packed up, and the backlights stay on (back in the day the mouse and keyboard where off a 'state of the art' gaming m/c with green backlight), also if you check MB for LED's you will probably find these stay lit.

Isn't that on purpose - for wake on LAN functionality?

In reply to a post by 69bertie:

One thing I have recently noticed is my computer's motherboard fed USB sockets are still usable (I use them for charging the phone) even though the computer is shutdown. Which means my gold rated PSU is still producing power even though it looks off.

In many cases this is deliberate, so the ports can be used for charging devices. I am writing this on a 6 week old Lenovo ThinkPad X1 Yoga, which has one of the USB 3.0 ports on the device and a couple of the USB 3.0 ports on the OneLink+ Dock permanently powered. These ports have a 'battery' symbol under the USB logo to denote they are permanently powered.

In reply to a post by 69bertie:

For some makes I could well believe it would cost some money but MK say otherwise for theirs. Zero cost on standby with automatic disconnection as soon as the USB plug is removed MK USB Tech specs

Are you sure? On which page of the Tech Spec does it say the USB Integrated Sockets power down when te USB plug is removed?

In reply to a post by MHC:

In reply to a post by 69bertie:

For some makes I could well believe it would cost some money but MK say otherwise for theirs. Zero cost on standby with automatic disconnection as soon as the USB plug is removed MK USB Tech specs

Are you sure? On which page of the Tech Spec does it say the USB Integrated Sockets power down when te USB plug is removed?

Page 5:

Dust proof USB port shutter
Zero standby power consumption, auto disconnect when plug
removed

Its certainly interesting as I haven't installed any USB sockets myself because unless they physically disconnect the power you cannot run a insulation resistance test with them fitted.

That said, the MK sockets are so expensive at retail that its kinda silly to even bother. I assume the op got them at bulk due to being an electrician.

Edited by alexatkin (Sun 31-Jul-16 04:45:58)

I'd have expected some power used, as you say for LAN wake up purposes but it still came as a surprise to find the USB sockets still live at switch off. Not that I'm complaining, very handy not to have to bother with USB plug in adapters.

In reply to a post by alexatkin:

In reply to a post by MHC:

In reply to a post by 69bertie:

For some makes I could well believe it would cost some money but MK say otherwise for theirs. Zero cost on standby with automatic disconnection as soon as the USB plug is removed MK USB Tech specs

Are you sure? On which page of the Tech Spec does it say the USB Integrated Sockets power down when te USB plug is removed?

Page 5:

Dust proof USB port shutter
Zero standby power consumption, auto disconnect when plug
removed

Its certainly interesting as I haven't installed any USB sockets myself because unless they physically disconnect the power you cannot run a insulation resistance test with them fitted.

That said, the MK sockets are so expensive at retail that its kinda silly to even bother. I assume the op got them at bulk due to being an electrician.

Go back and read the document again ... No where does it say the Sockets with Integrated USB have zero power consumption when not in use.

Many years ago the power button was a hard button that actually killed all power to the system. Then they moved to soft power buttons - the only way they can work is if the PSU is supplying power to the motherboard as that is where the power switching occurs.

Plus they bought in services such as wake on lan - the only way to do that is to keep the lan circuitry live otherwise it can't see the incoming power on instruction.

And as others have mentioned the USB power can be powered so they can charge devices even when the system is "off".

In the early days you could get away with changing the memory and the like just with the power switch off but these days you either need a power switch on the PSU to isolate the motherboard power or you have to unplug or switch off at mains.

Wake on LAN isn't the only service ... wake on mouse & keyboard nowadays requires USB power.