Csn I use two power supplies?

[mrsambo12]

Hi,


I have a few 200 and 250 watt power supplies. I have spent so much money recently that It will be difficult to shell out even enough for a new power supply to support all my new hardware. I was wondering if I could Mod my cases and install another Power supply in them. Maby use one for hard drives, cdrom, etc. Other for everything else. Is this possible? Is it safe for system? If so, how would I make both power supplies start up when I press start button and also go off on shutdown?

Also, On one of my computers, The sound the fan makes is always fluctuating. Sounds like they rev up and slow down. What could cause this? This system is as follows >

AMD Athlon XP 1700+ on abit kr7a-R with 256 mb DDR 2.5c.
1 7200 rpm 40g Hard Drive
Geforce3 ti 200
CD-ROM
Several fans of all types.
Power supply is generic 300 watt.


Thanks for your help

Sam R

[JigPu]

As long as a second power supply will fit into your case, you should be good to go! In order to get a second PS to turn on with your main PS, I have heard of people wiring a relay to be used as a switch. That way, when the main power turns on, it will cause the relay to make the second power on as well.

As for the fluctuating fan noises, there are only two things I can think of... First, you have a PS that regulates the fan speed based on the temperature of the air in the computer, OR it could be dusty. I don't know much about power supplies, but those are the only things I can think of.

Good luck with your mod!
JigPu

[Hoot]

You will have the best luck paralleling PSUs if they are close to one another in power capacity, ideally the same make and model. The changing speed on your fans is caused by changes in load on the +5V feeding the CPU core voltage regulator circuitry.

Hoot

[Dieni]

Mine has been running liek this since last May. Harddrives, Cd-Roms & Fans on one PSU, while the mobo, cpu & pci cards on the other.

I have connected a relay switch to one of the molex connectors. Than the relay switch is connected to the mobo connector on the other PSU. When I press the power switch, the relay automatically swiches the other PSU on. If i am not wrong you have to connect the relay to the green wire and a black one. Not sure abouu this thou better check.

[SteenkyBastage]

well, i just tried the link, and the site isn't coming up. hopefully they're just down temporarily...

http://www.hardwareoc.com/dualpsu.php

that site (when it's working) shows all about hooking up two psu's and different methods of linking them to turn on/off together.

good luck!

[stool]

Here's another; 2PSU (http://www.burningissues.net/how_to/power/psu.htm)

[MiseryQ]

Does the 3.3&5.0 outputs effect the 12v output?!?

I was thinking of going this route but my Antec has a strong combined 3.3&5.0v... My 12v out is only 11.9v...

[jboy]

Is it possible to run 2 PSU's in parallel, e.g., not using one for the 12v and the other for the 3.3 and 5v rails, but essentially doubling the capacity of the combined units ? It seems there'd be an advantage to this approach of providing a backup in case one of the units failed, the other would protect components from damage. Does any knowledgeable person, (Hoot?), know if when PSU's fail, they typically fail in a way that wouldn"t damage the other unit ? Or do they short in a way likely to take the other unit with them ? Just wondering..

[Krusty]

Originally posted by jboy
Is it possible to run 2 PSU's in parallel, e.g., not using one for the 12v and the other for the 3.3 and 5v rails, but essentially doubling the capacity of the combined units ? It seems there'd be an advantage to this approach of providing a backup in case one of the units failed, the other would protect components from damage. Does any knowledgeable person, (Hoot?), know if when PSU's fail, they typically fail in a way that wouldn"t damage the other unit ? Or do they short in a way likely to take the other unit with them ? Just wondering..

Hmm...I would think this could be accomplished by splicing all of the lines connecting to the mb together. This would make the voltages the same, but increase the current it can draw.

However, I am not sure if that would even work or not. I guess as long as the power button makes both psus come on, it should work.

[deathstar13]

hey guys i do have the one link http://www.burningissues.net/how_to/power/psu.htm
but i need another few links ,i plan on doing this asap.

i have my second one already doing some fans. also has anyone had a prob with the 7v mod and a psu? my 7v modded 120's arent seeming to fire up with this 300w slave psu? anyhow i left em on my 400w master. my main goal is the paralell 2 psu. as this thread was started .

i have everything done so far except the paralell connections on the atx line. thats my main concern is to get it correct on the first try and not smoke my mobo. no multi meter on hand :( any ideas on how to test?without mobo connected?
im not trying to highjack this thread as i think its the same questions. sorry if it seems that way.

thanks guys my system is rockin! hehee thanks for all the help.

[deathstar13]

ok mr sambo, just so ya know this mod does work! my rails are great! i might wanna go back and add my 3.3 rail also. plus i now have 700w psu! thats some smoken power!

[jboy]

Did you actually parallel the power lines on your PSU's, or just do the mod that turns 2 of them on at once and lets you use the 12v from one and the other for lower v. rails ? If you actually paralled them, they should be rock stable, hey ?

[deathstar13]

well after some testing i undid the mod. it seems i didnt get the push to stablize things as i thought.

i found it better to use both psu's though and ran the secondary for all my fans. this lifted my psu power to normal operational voltages i seeked. and less hassle.

for some reason when i switched my 7v modded 120's over it didnt like that at all and the fans wouldnt turn. so i did it as a secondary.