Ways to use a 2nd PSU in an external LC System?

[VectorRoll]

I am looking to add one of my Spare PSU's I have laying around here to my external Water Cooling System just to supply power to its Rad Fans and Pumps. I would like it to turn on when I turn on my Main PSU for my PC.

So I am wondering:
Does anyone here have any experience with connecting two PSU's together?

I have seen how people connect the Wires between the 24-pin Molex of the main PSU to the 24-pin Molex of the second PSU in order to turn on the second PSU just by turning on the main PC. This method seems like it would be the best and easiest way to add a PSU to my External Water Cooling System.

From reading about it I know which wires to connect, (the Green /PS_ON and the Black Ground). I also have all the spare Molex connectors and parts, (I.E. 24-pin and such) that I used for modding case wires to match my color scheme. So doing this would not be to hard.

I do have a question though. Something that I am curious about.

Are there any other ways to connect 2 PSU's besides connecting the both 24-pin connectors together?

Like say if it was possible to use the power from a 4-pin Molex on the Main PSU connected to the 24-pin of the second PSU in order to turn on the second PSU? I already have a 4-Pin coming from my Main PC Case to power the Fans which is why I am wondering about this idea.
Or
Some how using one switch in order to turn on two PSU's? Like say wiring the On Switch to the second PSU somehow while having the second PSU using that wire trick from its own Green to Ground? Is this even possible?

 

[nukemaster]

You only need to bring the green and a black wire from one power supply to the other one.

You do have another option and that is to get a 12 volt relay from an automotive store and have it act as a switch from the green to black on the rad/pump/fan power supply. 12 volts(black and yellow on the molex connector) will make it start the second power supply, when the 12 volts shuts off, so will the second power supply.

They do make several adapters as well to do just what you want(The one has a small resistor to place some load because some power supplies do not like running rails with no load).

 

[VectorRoll]

You only need to bring the green and a black wire from one power supply to the other one.

You do have another option and that is to get a 12 volt relay from an automotive store and have it act as a switch from the green to black on the rad/pump/fan power supply. 12 volts(black and yellow on the molex connector) will make it start the second power supply, when the 12 volts shuts off, so will the second power supply.

They do make several adapters as well to do just what you want(The one has a small resistor to place some load because some power supplies do not like running rails with no load).

Thanks for the reply.

I have seen those adapters. The one from Lain Li which looks like the same style as the one in the picture you have posted, and also the one Add2PSU. I am not sure if I want to buy it though. I can however make the one in the picture as I actually have enough spare parts already to do so.

You mentioned a 12v Automotive Relay being used. That sounds more like what I am looking for. You see I already have a cable coming out of the PC to my External Box that powers the Fans and Pumps. It is a 4-pin. If I can use a 12v Automotive Relay through it to turn on the second PSU in that box that would be great.
So...
I want to see if I got this method right.

1) I use the 12 Automotive Relay as the switch between the two PSU's.
2) I connect the two appropriate plugs from the 12v Automotive Relay to a 4-pin connector.
3) That 4-pin connector gets plugged into the Main PSU through one of its 4-pin connectors which in turns supplies the 12v to the second PSU through the Automotive Relay.
4) I then I take the other two appropriate plugs on the 12v Automotive Relay and wire them to the 24-pin (Green & Black) on the second PSU.

Is this correct?

I searched the web on this method and found this thread on another site that shows an image of a 4-pin molex connected to the automotive relay. He gives a brief description of the method and I want to make sure it is the same as what I am thinking of. (http://www.jonnyguru.com/forums/showthread.php?t=1683)

Is that similar to what you were explaining?

 

[nukemaster]

The automotive relay is a DC activated switch. So you bring it 12 volts from the power supply(via molex) and is just swicthes the green and black on the second power supply. When it looses that 12 volts, it shuts off.

So the relay being a single pole single throw type will have just 4 contacts. 2 of them will take power(black and yellow) to turn on the switch and the other 2 will connect green to black on the second power supply(black and green from psu #2).

 

[VectorRoll]

The automotive relay is a DC activated switch. So you bring it 12 volts from the power supply(via molex) and is just swicthes the green and black on the second power supply. When it looses that 12 volts, it shuts off.

So the relay being a single pole single throw type will have just 4 contacts. 2 of them will take power(black and yellow) to turn on the switch and the other 2 will connect green to black on the second power supply(black and green from psu #2).

Cool thanks. I'll give that a shot and see how well it works.
Thanks again.

 

[VectorRoll]

The automotive relay is a DC activated switch. So you bring it 12 volts from the power supply(via molex) and is just swicthes the green and black on the second power supply. When it looses that 12 volts, it shuts off.

So the relay being a single pole single throw type will have just 4 contacts. 2 of them will take power(black and yellow) to turn on the switch and the other 2 will connect green to black on the second power supply(black and green from psu #2).

Finally finished my Adapter. Took me a while to find my wiring connectors that connects to the Relay but I finally found them in one of my tool boxes and was able to finish it. The wires are all crimped, soldered, and sleeved. I did run out of the Red Male 4-Pin plugs so I am temporarily using a clear until I get another one.
Anyways I tested it with two power supplies and it works perfectly.

Thanks for the help.


By the way here is a picture of it.

 

[nukemaster]

Very nice work.