On my good old PC there was a good old type of on / off switch on the front plate
this switch also control via the output on the powersupply (PSU) my monitor,
printer, scanner, modem, router, hub, external water pump, and all other things I have.
BUT now I have updated my PC to a more modern type with more GHZ and so on, this new PC uses a ATX powersupply.
This PSU have also a poweroutput plug, but it is ALWAYS ON !!! Not soo good when electricity is not for free !!
There are two ways to solve this: install a relay inside the PSU or install an electronic mains switch with no moving parts..
They have different price and performance, the choice it up to you..
First check that your ATX powersupply has both an input and an output mains power plug.
Add two new wires, a red and a black for +5 volt and ground, to drive the relay or electronic switch.
The module I'm using is a Power Fin 25A peak, 10A Cont. 250 Volt AC electronic switch,
The controll input on/off voltage is 3-15 volts and only 5 mA
Here is the control input wires soldered and secured with heat shrink tube.
Cut the connection to the output connector. The white line is the cut away copper track.
The switch pins are soldered to each side of the broken track.
When done secure it with hot-melt glue, use plenty..
Now it looks good and safe.
When I was done with all the other stuff, I removed the safety grid behind the fan blades,
now the air noise is a bit reduced, if you put in a finger it's not a big problem,
the fan blades and motor is made of plastic and is light weight, so it does not harm your fingers.
I have also cut away every secound metal part in this air gap, to improve air flow.