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Dual PSU How-Tos

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stool

Senior Member
Joined
Dec 20, 2000
Location
Albany, NY
As the question of hooking up dual PSUs comes up quite frequently in the forum, I have gathered a few links that show some differing methods of accomplishing the same thing.

To use a relay, try Speedy3d's method . It also includes a wiring method.

To hook up two AT PSUs check out Procooling's article.

My personal favorite, which doesn't involve cutting your PSUs wiring, is found at Burning Issues

One I have found is here;
http://www.picard.demon.co.uk/atx.htm

Here's a new one another forum member found at Procooling
 
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IFMU

The Xtreme Senior Nobody
Joined
Jun 21, 2001
Excellent. Thanks for the links there. Ive seen them all before but have lost them all great to have them somewhere all together I can find what Im looking for.

Question. Would doing that last mod make the psu's capable of supporting dual board?

Im interested in trying to save some dough so I can get a little better CPU's or even some extra ram. So can I do this and be able to use 2 of my present PSU's and use it as one on the motherboard? Would this support it ok?
 

aulddm

Registered
Joined
Apr 11, 2002
Location
Aberdeen, Scotland, UK
IFMU said:
Excellent. Thanks for the links there. Ive seen them all before but have lost them all great to have them somewhere all together I can find what Im looking for.

Question. Would doing that last mod make the psu's capable of supporting dual board?

This is what i have been trying to find info on, no such luck yet.

I want to take approx 6 MB and run them from say 4 PSU, seeing as each PSU separately is not under full load, no cd-rom, floppy drive, etc. bare bones number cruching machines (may even go completely diskless). Does anybody have anything on this approach???????

cheers,

Dave
 

RoadWarrior

Senior Member
Joined
Nov 25, 2001
Location
Niagara Falls, Ontario, Canada
Damn, now I am more confused. I want to have a second PSU in parallel with my first to stabilise the 5v line under load. Now the procooling article which is the only one which actually deals with issues other than just getting the second supply to turn on, says to isolate the cases of the PSUs from ground for Parallel or Serial use, then it tells you to connect the two grounds together when you wire it for parallel. Now I understand totally about isolating the cases for serila use, but for parallel when you are going to connect the grounds together anyway?????? I don't get it. Besides which, it's nearly freakin' impossible to isolate the cases from the grounds in the long run anyway, because of those cards grounded to their backplates through the 0v to the case, which the PSUs are screwed to.. . .. Well You could insulate the PSUs I guess, but I want a damn ground somewhere, I'm not leaving all the grounds floating. If something grounds I want it grounded through ground, not my freakin' motherboard.

So was that some stupid "abundance of caution" thing or do you really have to isolate the case grounds and how and why is it different to tying the output grounds together?????

Road Warrior
 
OP
stool

stool

Senior Member
Joined
Dec 20, 2000
Location
Albany, NY
Just remember that the Procooling article only involves AT PSUs. It was cautioned by Hoot some while back to not try that method with ATX.
 

mark

Member
Joined
Aug 7, 2001
Location
Scottsdale, Arizona
I have two questions..

I have dual PSUs currently.
I've been running them for over 6 months.

My second PSU is a 300w that runs an 86w peltier, and a bunch of case fans..

I used speedy3d's way seen here.
casemodp3_6.jpg

My first question is..

Do I need to have some kind of load (like 1 Amp) on my second powersupply on the +5v line to have it produce it's maximum Amperage or Voltage on the +12v line?
(I have heard a people say this)
If you have a multimeter, and can test this, that would be cool.

My second question...

I have seen a few dual PSU guides that have the Gray(powergood) {pin7} line and a Black(ground)line connected.

wire2atxpsus.gif

Here is the article
http://www.commongrounds-pc.com/Articles/dualpsu.html

This guide also has you connect the Gray(powergood) line and a Black(ground)line.

Picture1.jpg

Here is the article
http://www.picard.demon.co.uk/atx.htm

even here has the powerok line grounded..
http://www.burningissues.net/how_to/power/theory.htm

I am wondering if this is really needed.
Please shed some light on these things.

thanks,
mark
 
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mujgy

Registered
Joined
May 11, 2001
Do I need to have some kind of load (like 1 Amp) on my second powersupply on the +5v line to have it produce it's maximum Amperage or Voltage on the +12v line?

This only apply's to AT power supplies. ATX supplies run two seperate voltage regulators for the 12v line and the 5v/3.3v. except for the antec TP series which have three regulators.
 

Since87

Member
Joined
Jul 30, 2002
Location
Indiana
RoadWarrior said:
So was that some stupid "abundance of caution" thing or do you really have to isolate the case grounds and how and why is it different to tying the output grounds together?????

Road Warrior

You don't have to isolate the grounds in the parallel case. There may be some advantage to picking the right place to tie the grounds together. You do want to try to tie the grounds together at only one point. Otherwise you can have what's called a ground loop which can cause weird effects like 60Hz hum on your speakers. A ground loop could possibly even result in instability in your system, but it's not going to damage anything.

The serial case is another story. You are risking significant damage if you do not know what you are doing.
 

sendatooli

Member
Joined
Jan 13, 2001
you guys are terrific!

you guys are terrific! i was on my way over here to ask this very question figuring it hadn't been dealt with before. silly me, not only is it dealt with it is sticky!

anyways, the articles posted herein actually made me decide NOT to do this! my main psu in the machine i was going to do it to has a 550 watt.
i have a nice house and a family. i cannot afford a fire!
now i know if done right a fire is unlikely. i also have a decent knowledge of electronics. the diagrams are very straight foward.
however, anything that can go wrong will. this could prove dangerous even if done "right".

i did not mean to spoil the party. i am just glad i read the fine print that allowed me to make my decision.


thank you,
sendatooli.
 

wildfrogman

Member
Joined
Jul 13, 2002
Location
Sitting at my computer playing UT2004.
So, what would the results be on two delta 300 watt atx psu's that have 245 watts combined on the 3.3 and 5v if they were combined in parallel to the motherboard so in theory you have 490 watts combined? What exactly could say go wrong even if all is wired right and grounded and such...possibly each ps not responding the same and giving slightly different power?
 

The Overclocker

Member
Joined
Aug 21, 2001
Location
Milton Keynes, UK
(rases hand)

as the problem is not the 12v line - usally the 5v line which i shared with the 3.3v line, why not seperate the 3.3 and 5v lines so one powersupply is power the 3.3v line and the other is powersing the5v line, as these are usally (not laways - the antec trupower ones done) powered one the same line, they should be able to delive 2x the power
 

Crazy Jayhawk

Member
Joined
Jul 14, 2001
Location
Hutchinson, KS
Re: Dual PSU placement

tripwire said:
I have wired the PSU correctly... and got it all working with a switch to turn it on and off. But, now the delema is placement! Where do I place this damned extra PSU. Even with my rather large SX830 Antec case, it doesn't really accomadte the extra PSU.

http://www.antec-inc.com/en_wkstion.html
You could mount it in the bottom front, underneath the hard drives. You'd just need a place for the cord to go through the case.
 

bldegle2

Member
Joined
Feb 18, 2002
Location
Floyd, VA
Dual PS's

here is some additional info.

i modded a second PS and did some extensive wire removal, the P4 connector, the single extra weird plugin, and the whole Mainboard wireloom.

now i have a slick second PS with only powerlegs and some new LED fan connectors coming out, along with the green and black wires for connection to first PS, all under red acrylic covers.

couple of things that will make your experience easy, first, two sets of two wires go to the mainboard plug, a set of orange and set of black, ID those first, cut them back into the PS, and connect them back together (yes, you have to do this), black to black, orange to orange, then cut all of the other wires in the main loom and the other two i mentioned. no need to insulate the ends if you use an acrylic cover and they are cut short enough, if you reuse the metal cover, the cut ends should be covered for saftey sake.

and one other tidbit of info, as long as you have a grounded wiring system in your house (takes three prong plugins, not just two), then you need only to connect the green wires together to get the suckers to fire together once all put back together. the additional black wire is unneccessary, but it doesn't hurt to connect them if one so desires.

since this is all going in a see through acrylic case, i plan on shortening the outgoing powerlegs (gotta be the easiest part of the whole operation)so the wire clutter of a present day box setups is a thing of the past.

hit me with an email if you have questions.

baldy:cool:
 
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Dhamali

New Member
Joined
Sep 5, 2002
Location
South Jersey
Broken Link ???

The link to the CommonGrounds articles are not working. Can you tell me where can I find them ?

I searched that site for "dual psu" but came up empty..

D
 
OP
stool

stool

Senior Member
Joined
Dec 20, 2000
Location
Albany, NY
I have eliminated the Common Grounds links, as they are no longer functional.
 
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