Powering a remote wake up switch from automation PC

[Simon Ryley <simon.ryley@xxxxxxxxxx>]

I'm fitting an embedded micro with a webserver to my automation pc to
allow me to wake up the automation pc remotely from standby.

For power saving reasons, the pc is normally in S3 standby, and wakes up
through scheduled tasks when things need to be done.

I'd like to be able to wake it up remotely over the web when I want to
do maintenance on it, so I'm fitting a micro connected to the power
switch to bring the machine out of standby.

The micro needs a regulated 5v or a unreg 12v supply to run.  As an
elegant solution, as it is fitted inside the pc chassis, I'd like to
power it from the PC ATX power supply.  Problem is when the machine is
in Standby, all the fans, drives etc are turned off.

Does anyone know a source of permanent 12v or 5v from the PC power
supply that I can use to power the micro?  I've measured the standby 5v
on the USB port, and it seems to be more like 6v so isn't suitable.

Thanks,

Simon