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combining 250PSU and a 90w

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MoonWolf

Fold For 32!
Joined
Jun 27, 2002
Location
Texas
Can I combine a 250w PSU with a 90w PSU? All I have to do is cross pins 14 and 15 of the 90w with 14 and 15 of the 250w and connect pins 7 and 8 to eachother on the 90w? How much more power will this give me? Is this all I have to do?

-Wesley
 

larrymoencurly

Member
Joined
Jul 14, 2002
8 is Power Good, an output.
7 is ground

14 is Power On, also an input
15 is ground

Connecting all the grounds together may be a good idea, but you never want to ground an output, like pin 8. You also never want to connect the output of one PSU to the output of another PSU or they'll argue with each other.

I think the only safe way to use two regular PSUs together is by having part of the computer powered off one of them and the rest of the computer powered off the other one.
 

deathstar13

FSB FRIEK
Joined
Dec 24, 2001
argue? i never heard of this. not saying isnt true just never heard it.seems to me if there is a load on the line niether psu would have a problem with it.ive run 2 psu's in parallel. just the 5v line but im gonna do 2 psu's fully paralleled.

i didnt see any problems with it. did get a stronger output.
 

Mr.DLucey

Member
Joined
Jul 8, 2002
MoonWolf said:
Can I combine a 250w PSU with a 90w PSU? All I have to do is cross pins 14 and 15 of the 90w with 14 and 15 of the 250w and connect pins 7 and 8 to eachother on the 90w? How much more power will this give me? Is this all I have to do?

-Wesley

Why are you doing this? Are you having a problem? I have 2 PSU's hooked up in my back-up computer. I had to do this because my old compaq came with only a 175W PSU. It did not have enough power to run a PCI video card, came with on board video. One PSU powers just the mother board and the other powers every thing else. Works just fine.
 
OP
MoonWolf

MoonWolf

Fold For 32!
Joined
Jun 27, 2002
Location
Texas
New system coming... my Xp 1600 will be here in a few. Combine that with a nice little K7S5A powerhog, youre already sucking the 250w dry. Need extra power.

The 90w is for devices. In fact, I'm not even sure this is gonna work, but methinks its worth a try.
 
Last edited:

Mr.DLucey

Member
Joined
Jul 8, 2002
Why don't you power the motherboard and the hard drive with the 250W and power the cd drives case fans etc. with the 90w.
 

larrymoencurly

Member
Joined
Jul 14, 2002
What I mean by the two PSUs arguing with each other if they're connected together is, suppose PSU A thinks the output should be 5.05V and PSU B thinks it should be 4.95V. If the output is 5.00V, won't PSU A try to raise the output while PSU B will try to lower it? I've read that if this adjustment occurs at just the right rate, there can be wild oscillations that can destroy one of the PSUs.
 
OP
MoonWolf

MoonWolf

Fold For 32!
Joined
Jun 27, 2002
Location
Texas
Actually, I intend to run the motherboard and the CPU off of the 250w PSU and the HDD and CDRoms and case fans from the 90w. all I can do is hope and pray that the 250w puts out enough power for the K7S5A and the CPU + Ram and video card. Last time I ran an Athlon XP on this PSU WITH an HDD and CDROM and a few fans it would freeze upon entering windows. I hope the 90w can make up for the power shortage.

Any suggestions would be welcome. (note: I don't have the money to just go out and get a new PSU... thats why im doing this in the first place.

-Wesley