Two Powersupplys in one case?

Firebat

Gawd
Joined
Nov 9, 2005
Messages
875
I was thinking, why not run the l.e.d. lights and my case fans off a second powersupply? Everything else would run off the first powersupply. I could find room in my case to put the second power supply in so right now that's not an issue.. The power supply i have in right now is 420 Watts, it seems to be working just fine on its own, but i just want to see if i can run two seperate powersupplys simotaniously. My other one is not in use and it's 300 Watts. Now the only problem i can foresee, is how to boot this second power supply. Any ideas?
 

IntimidatorX

Weaksauce
Joined
Nov 1, 2004
Messages
119
Just connect the Normally Green cable from the ATX plug on the PSU to any other Black one.

atx0cq.jpg


Like this,

atx-plug.jpg
 

SarverSystems

Supreme [H]ardness
Joined
Feb 9, 2002
Messages
7,408
That's overkill if you ask me. Running a few (even a hundred or so) LEDs hardly uses any power at all. I can't imagine a fan using enough to warrant a whole second power supply either.

Now if you had LOTS of fans, and CCFL lights, and other power hungry devices in there, then maybe a 2nd PSU would help.
 

LesterOfPuppets

Limp Gawd
Joined
Nov 14, 2005
Messages
143
<disclaimer> Making a mistake during this kind of procedure is a good way too destroy hundreds of dollars worth of equipment. I'm not sure if I would do this in your situation. I did it when I needed to get this computer running, yet didn't have an adequate PSU.</disclamer>

I went off of a website that I can't find now...

Your case layout and PSU positions will dictate where to cut the wires...

PSUa= the one that powers your motherboard
PSUb= the one that doesn't

1. snip the green wires of both wiring harnesses.
2. hold the freshly cut wires from PSUa and the wire that goes to PSUb together with the ends lined up, and slide some heat-schrink tubing over them.
3. Then solder all three together
4. hit that heatshrink with your lighter.

Here's a crappy schematic...

PSUa
|
|
---- PSUb
|
|
mobo power connector


5. Repeat steps 1-4 with one of the ground wires (use ones with the same position on the mobo power connector)

here's a pic of my setup:
PSUa up top, PSUb on the bottom
http://www.flickr.com/photo_zoom.gne?id=73002918&size=l

PSUa handles mobo and vid card only, PSUb handles everything else. PSUa has a power switch, and when it is off, PSUb is on, powering the case fans even when computer isn't running.

You can see the splices to the left of the cpu, probably not the best spot for them, but this is not how I originally had the PSUs positioned.
 

jpmkm

That Ain't Mayo On My Lip...
Joined
Oct 30, 2001
Messages
5,773
I can't imagine your fans and leds draw more than half an amp total, so having a 300W power supply just for that is extremely overkill. :p
 

Silent Assasin

[H]ard|Gawd
Joined
Aug 1, 2004
Messages
1,120
Or instead of cutting the wires on both power supplies, do what I did with a friends computer.... I cut all 20 wires from the P1 connection on PSUb, wrapped them all except for the green wire and one ground wire so that none of them would tocuh, I cut them far enough back so they wouldn't take up case space either. I then extended to two wires and attached them to a simple toggle switch in the front of the case right next to the power switch. IMO, much safer....
 

AreEss

2[H]4U
Joined
Jul 5, 2005
Messages
2,180
Definitely a job for PC Power & Cooling, not ... whoever the hell made those junker PSUs. ;)

If you're feeling frisky, what you can do is put an old AT PSU on a volt-driven relay. An ATX PSU WILL get upset without certain loads, and it DOES shorten the lifespan noticably. AT PSUs do not suffer from this. Most 'drive cage' power supplies are derived from AT designs.
AT is a hard switch, versus ATX's softswitch. To turn on an AT PSU with an ATX PSU, you only need to find a way to close the switch circuit. A simple relay can easily accomplish this, taken from any voltage source. Voltage presence to close, and you're set.
 

Frank4d

Gawd
Joined
Oct 29, 2005
Messages
715
I have seen the wiring diagram in the FAQ before. It says to connect grey (PS_OK) on the second PSU which is an output that doesn't go anywhere... to black (ground). Can someone explain WHY I would want to short a PSU output that doesn't go anywhere to ground?
 

demografik

[H]ard|Gawd
Joined
Mar 25, 2002
Messages
1,055
AreEss said:
Definitely a job for PC Power & Cooling, not ... whoever the hell made those junker PSUs. ;)

If you're feeling frisky, what you can do is put an old AT PSU on a volt-driven relay. An ATX PSU WILL get upset without certain loads, and it DOES shorten the lifespan noticably. AT PSUs do not suffer from this. Most 'drive cage' power supplies are derived from AT designs.
AT is a hard switch, versus ATX's softswitch. To turn on an AT PSU with an ATX PSU, you only need to find a way to close the switch circuit. A simple relay can easily accomplish this, taken from any voltage source. Voltage presence to close, and you're set.

He speaks truth. During the summer my bedside fan broke (by broke i mean it drank alot of beer, but that's a different story), so I hooked up a Sunon 120mm to an old AT psu and chilled out :)
 

Firebat

Gawd
Joined
Nov 9, 2005
Messages
875
It works, What i did was i cut one of the black wires and the green wire from my second powersupply on the atx motherboard connector. Than i twisted them together and saudered them. Than i put it in my case hooked up the fans, lcdscreen, and leds, to it. It worked :) They do run 24/7 even if my computer isn't on, but thats ok, it is almost always on. When i get the pics from this i will post them back here. The way it's set up its good for a laugh.

PS. I now have 720watts. Can you say bragging rights? Thanks for all the help and not telling me anything that would blow my powersupply's up. :)

Sence the other powersupply is in the other corner it made it impossible to do the diagram some of you posted.
 

Anime_Fan

[H]ard|Gawd
Joined
Mar 1, 2004
Messages
1,207
I've been thinking about running a second cheap PSU for my water cooling pump, fans, and ccfls. Might be easier that way to hide some wires and stuff if I dont want to worry about hooking up things like hard drives and stuff and just concentrate of hiding the fan wires and all that.

Been thinking about building my own cube case for that though.
 
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