Originally Posted by N2Gaming
Ok this is probably an old thread but I read every post as I am interested in doing this w/my [Project] Black N Blue. I am wondering what makes the power supply know to turn on and how the power button works. does the mobo have a charged capacitor that supplies low voltage/current to the power switch and when you push the momentary power button it in turn sends a signal through the already charged mobo circuits and finally sends a signal to the power supply to turn on. So my question is this. when you push the power button again it tells the mother board to turn off and that same circuit in the mobo tells the power supply to turn off. Ok if your still following me on what I'm thinking then wouldn't the mobo just supply both power supplies with the same on and off circuit with in itself. I don't understand how the power supply turns on and turns off. Is there a separate pin for the off circuit or is there some kind of temporary surge stretching all the way from the chassis power button to the power supply. If this is the case I don't see how having a jumper wire to pin 14 and 15 would hurt the mobo. If I understand it correctly the mobo only supplies a momentary current to the power supply each time power button is depressed for on or off. or is this wrong. So If both power supplies were jumped together via pins 14 and 15 then there should be no harm done. Please if you are confused by what I'm thinking then that means I'm not alone. I guess what I'm trying to figure out is the mobo suppling a constant continuity to the power supply or is it a momentary signal every time the power button is depressed? Can any one clear this up for me??? Iâ€™m hoping to turn both power supplies on and off with the push of one button, Thanks here are some of the links referenced a couple of posts earlier in this thread
A power supply has a rail called the 5VSB (SB = stand by). This is on a separate circuit to it's main rails (12V, 5V, 3.3V). The thing with the 5VSB is that it is always on when the PSU is plugged into the outlet. It is constantly supplying power to the motherboard.
There are two ways to turn a PSU on. Either physically jump wires 14 and 15 or use a momentary switch connected to the motherboard which basically jumps wires 14 and 15. The motherboard isn't constantly supplying power to the PSU through this, is it just a circuit that is completed with a momentary switch to tell the PSU to turn on. Once a motherboard detects that the power supply is giving it power it starts its boot sequence. This may not be a completely accurate description of the motherboard/PSU relationship, but I know the way a PSU is told to turn on is through completing the 14/15 pin circuit (well, pin 14 and any ground). If you want to turn both PSUs on with the same switch, you need to use an adapter plugged in between the main PSU ATX plug and the motherboard which are not easy to find. Something like this:
It's essentially a 24-pin extension cable with an extra set of 14 and 15 pin wires spliced in. That way both PSUs get the power-on signal from the same switch.