Re: PC Power control, how?


<jhewitt@xxxxxxxxxx> wrote in message
news:4mm52254p49j97go6m1tf7l55jksdvh8ok@xxxxxxxxxx
Thank you for the help

On Wed, 22 Mar 2006 12:58:41 +0100, jhewitt@xxxxxxxxxx wrote:

The power ON button is connected to the motherboard with a blue/white
twisted pair. The mother board has no power, and the power unit is
turned OFF.
How does/can operating the Power pushbutton turn on the Power Supply?


Because the motherboard does have power. One of the supplies from the power
supply is '5v SBY'. This 5 volt line is energised even when the power
supply is 'off', as long as mains is supplied. It's function (apart from
the power button) is to keep memory alive when the PC is in Standby mode.

Since this supply is available on the expansion slots, cards should not be
inserted or removed when the mains is connected, but the computer is
otherwise off.


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