Overclocking / Modding → How to synchronize 2 PSUs in 1 PC?

I have huge file server i need to run, it has 12 200gb HDDs. Instead of buying some expensive psu ($300 and more) i want to buy 2 cheaper ones for around $100 each. The problem is that i don't know how to sync them, so they would turn on and off together. Case is full-tower and PSUs are ATX, not server ones.

You can use the main one for the mobo, boot drive and some of the 12 HDs. Use the second one for the rest of the HD and CD-ROM. Setup the first PS normally. Ground pin 4 and 6 of ATX connector of second PS and use the on/off at the back of the PS.

P.S. There is not much difference between 2 $100 PS vs 1 $300 PS.

There is - $100

Any way to make them work as a whole? So they would work off 1 power button?

For the sake of arguing (not that I like to argue), if you can afford 12 HD in your system, $100.00 seems nothings.

No, I do not know of a way to combine two PSUs together. My suggestion should work (with minor annoyance), you have to power up the second PS b4 first PS. In shutdown, you have to power down the second PS.

I've done this before when I had a large file server. It takes some jury rigging on your part, but for the most, its pretty simple. The only way you can combine them to just one button is if you have a compatible switch for your desktop (custom). But if you do the combined switch, you will always have to shut off the hard drives seperately from the computer system due to timing. If you hit the power button to start shutdown, it will immediatly shut off the hard drives which would cause windows to freak out on shut down. So it does have its down falls as well.

What I recommend is getting the power supply, finding the specified pin outs and cutting them off the connector completely. Cut it off high enough where if you want to rebond them together, you can. Run a pair of leads to a toggle switch, and wire it together. Mount the toggle switch any where you want. I put mine on top of the file server as I had both power supplies in the same case. Before power up, turn hard drives on, and then bring your computer up. The rest is pretty self evident.

I think I might have read about something like this before, but I may be very wrong as I try to remember it.

I think you take the green & black wires from the ATX connector of one PSU and connect them to the green & black wires of the ATX connector that hooks up to the motherboard.

Again, I may be completely wrong. Can somebody clarify? I think I read about this before somewhere.

You wanna use a rigged PSU setup in a server with 12 HDDs? I can't see how saving $100 is worth the risk of damage to that investment...

Flip the one that supplies to just drives on first, then the mobo one on second...

there is this

»www.newegg.com/Product/P ··· 17153021

680Watt

or this

850Watt with 4 12Volt rails@17AMP's each u could power two computers with this much power

»www.newegg.com/Product/P ··· 17703002

Alright heres my input because i HAVE done this. I had one PSU for my computer and another for my peltier (i used an ATX for a little bit).

Alright what you do is on your main PSU, the one attached to the motherboard, take a +12V and a com from one of the connectors and attach it to a 12 volt relay.

Then from the second power supply, strip some wire around the green one in the huge ATX cable. Do the same with a com on the PSU as well. Crossing these two wires will jump start the computer. Strip some wire around the com as well.

The attach the PS_ON(green) and the com to the switch on the relay.

The result will be this: When the first power supply turns on, it will activate the relay which will close the PS_ON on the second PSU and thus turn it on. When the first power supply turns off, it will open the relay shutting the second PSU off (There may be about a second delay as the power drops, the relay throws and the second PSU shuts off).

Be advised though: An ATX power supply REQUIRES a certain load minimum on the 3.3, 5 and 12 volt rails. I think you'll have teh 5 and 12 taken care of but read the details on the power supply to add a load on the 3.3. You may need to get a power resistor (one of those thick blocky ones) and use ohms law, v=ir, to put an adiquate load.

Hope this helps!

Now that's what I wanted to hear.
What kind of relay have you used?

ok let me get this straight you have all this data and you want to use a jury rigged power supply? This is probably not the time to be cheap about things especially if you are dealing with that much info.

People stop teaching me please, I know what I'm doing and I'm going to do it. If I'm gonna ruin everything, that's my problems, thank you.

Mmmm, not sure. I got it from a local science surplus store. Its a 12 volt solenoid relay. Basically when enough power is sent through it, it triggers the solenoid which activates the switch.

I think relays of this sort can be gotten from radio shack or something. The PS_ON line doesnt carry much current at all so thats not a worry; i think solid state solenoids could be used. Their are smaller, require less power and dont "click" (although i found the click helpful during testing to make sure it works).

Just remember to avoid line undervolts put a load on your 3.3 rail. Otherwise all the things people are fortelling WILL occure.

So heres how you do it:
Your solenoid will have a part for power: This is where you attach leads from the main power supply (Main will now be the power supply attached to yourmotherboard). Test it then. If when you press the power button and the computer starts up you hear a "Click" your good.

Then you need to intercept the PS_ON line from the aux PSU (the PSU NOT connected to the motherboard). Instead of lobbing the end off the large ATX connector, i carefull stripped back some wire halfway down the line on the PS_ON line. The PS_ON line is the only GREEN wire. Any black (com) line can be used and follow the same procedure and strip back. I then soldered leads of same color (so not to get confused) at the strip points and then covered with electricians tape.

Now heres where a little guess work came into play: On a relay there may be 3 points: a common point, and then an A and B point. Basically, when there is no power to the relay, Point A and Point common are closed. When there IS power, points B and point common will be closed. Thats your ticket.

You want the ones that when power IS applied to the relay, the points are closed. Thus bridging the PS_ON and the com from the aux PSU. Therefore when ever the main powr supply turns on, it activates the relay and turns on the aux PSU.

One more thing: Some people say that this method of "jump starting" or "hot wiring" the PSU isnt good for it. They recommend to put a variable resistor in series with the PS_ON line. With the variable resistor in place (start with LEAST amount of resistance), start trimming it up. Once you reach a point when the relay shuts off, trim slightly back. This way there is the LEAST amount of current going through the PS_ON circuit AND there is less of a delay during shut down as the 12V rail from the main PSU takes a few seconds to drain completely.

Hope this all helps and you can get it to work.

Coolermaster has a cable they sell with the CM Stacker that allows to connect 2 power supplies together:

Q: How do I install two power supplies at the same time?
A: The idea of installing two power supplies at the same time means that one serves as the primary PSU and the other one as the slave PSU. A parallel cable for the slave PSU will come along with the package, hence, different from redundant PSU concept.

»www.coolermaster.com/ind ··· rial=106

850w geeze could run a quad AMD64x2 4800+ system with that. not that a 4way AMD 64 system exists lol.

There are plenty of 4way operteron (A64) systems out there, as well as 4, 8 and 16way XEON systems

however, they usually have bigger supplies than that. My opinion is that psu is targeted at a smaller (or low end) dual proc system with several hard drives.

the last server I purchased, a dual xeon, came equipped with dual 930 watt power supplies... it also has 10 drive bays, 8 of which are filled with 10krpm drives

dual 930 watt PSUs? Thats like running a vacum cleaner 24/7!!

wow now thats lots of juice. did those servers run on 120 or 240 lol?

it came with cords for both 120 and 230 ... I have it connected to the UPS (2200VA rm smart-ups) via the 120 cords, and the ups is connected to a 230V-30A twist-n-lock outlet

the server is very quiet, its the most silent one in the room... all the fans are managed by an on-board supervisor system