PSU rigging 2nd PSU to turn on and off (not the typical setup)

Hi all,

I've got a mini itx board which runs from a 12v socket on the back of the botherboard and doesn't use the typical atx PSU's.

The problem i have is that it can't provide the power to user 5 hard drives. The most it can do at a time is 3.

What i'm wanting to do is use the original case PSU to power the hard drives for the time being but need to know if its possible to make the PSU switch on and off via the green wire when the motherboard does.

 

You could use the output of the ITX PSU to drive a relay which would connect the green wire to ground.

 

There's an off-hand (read: very unlikely) chance that your motherboard offers a staggered startup, so that your hard drives don't all spin up at the same time. Might save you the trouble of having to rig up a second PSU.

 

Like hitman said, connect the output to the green wire on the PSU, to start it up.

 

It's possible and you don't need a relay. I build a loom, using an ATX extension lead, some green and black cable and an ATX male plug, that you connect to the output of a PSU, connect the other end to the motherboard and I wired a 3rd ATX connector to the black and green leads. This 3rd connector connected to my 2nd PSU.

Just use the green and any black lead to power the second PSU.

 

if im hearing remeniz right, and what i would do, is connect the green wire from the 2 PSUs together and ground the PSUs to each other. when the motherboard grounds the green wire, it will ground both PSUs and they will both turn on.

 

hitman had it right...

For the rest of you:

He has a motherboard that uses a brick, similar to a laptop. There is no green wire, and theres no easy way to access one.

Pick yourself up a cheap NO (normally open) 12v relay from Radio Shack, hook the input coil leads up to 12v and ground from a molex connector on the motherboard, then hook the green wire from the case psu up to one side of the output, and a ground from the case psu up to the other side. Once the system powers up it will close the relay, and complete the case psu's turn-on circuit.

If you need a diagram, I can draw something up in paint when I get home.

 

ahh, in that case:

 

be very careful that that the power from each PSU doesn't meet at any point as the difference in power fluctuations could damage your hardware

 

You mean like this?

OP:

What mini itx board do you have?

 

Not a bad diagram, but in this case the ground for the green wire needs to come from the case psu, or both grounds for each psu need to be combine so there's a common ground.

 

i think combining grounds would be easiest for wiring, but either way would work.