Daisy Chain 2 PSUs: Safe?

PSUs: The source of DC power for all components in the PC & often a big noise source.

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digitalfeed
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Daisy Chain 2 PSUs: Safe?

Post by digitalfeed » Fri Feb 16, 2007 7:52 pm

Is it safe to daisy chain 2 power supplies together? Are there any draw backs? Things to keep in mind?

I came across an old thread titled, Can I use 2 pico-psu's together to power my HTPC?

I want to get rid of my PSU but I don't think using one PW-200-M is enough. My estimates tell me I'd be pushing the PW-200-M very close to its limits.

So, why not use something like this:

Image

I know I don't neccessarily need two PW-200-M, but I don't mind getting two to have some room to grow.

What are your thoughts?
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jhhoffma
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Post by jhhoffma » Mon Feb 19, 2007 6:45 am

Doesn't sound feasible like that. But it depends on what you mean by "daisy-chain", if you mean connect them in series, then NO you cannot. Series voltage is additive so 12v into another 12v is 24v...not good for PC components.
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Elixer
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Post by Elixer » Mon Feb 19, 2007 7:54 am

As he said, it depends on what you mean by "daisy-chain" If you mean wiring the power supplies in parallel I would say that it might work, but is probably a bad idea to try. The picture that you have there is a device that simply turns on both two power supplies on simultaneously when it's signaled from the motherboard when you puch your power button. What most people do when running two power supplies is run the motherboard and processor from one and then all of their other devices (hard drive, video card, ect) from the other.

lm
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Post by lm » Mon Feb 19, 2007 8:48 am

Those DC to DC PSUs usually make the +12V just a pass-through, and thus require 12V DC as input. Then the +12V capacity only depends on the external brick and how heavy the passthrough cables are.

I recommend that you borrow a power meter that kind of clamps around a wire without touching it (somebody knows the name for sure) and connect a spare regular PSU to your HTPC, then measure the actual needed +3.3V and +5V when stressing your CPU, GPU and drives the way you need.

You might be able to use 2 identical PSUs in parallel, but definitely not in series. You could also try to use the other PSU just for drives and other just for mobo or sth like that.

digitalfeed
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Post by digitalfeed » Tue Feb 20, 2007 2:59 am

I believe the adapter connects two PSU's in parallel mode. I've only worked with car audio so I have a basic understanding using speakers with impedances and acoustical output volume in parallel.

Could someone confirm this via the following link?

http://www.performance-pcs.com/catalog/ ... s_id=21193
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jhhoffma
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Post by jhhoffma » Tue Feb 20, 2007 7:11 am

It's what Elixir said. It turns on two PSUs to run different devices. The connector with one cord on it runs to the ATX connector on the second PSU which is not connected to the mobo and feeds it the "power on" signal.
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digitalfeed
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Post by digitalfeed » Tue Feb 20, 2007 11:08 am

Oh, I see what you're saying.

So just to confirm, the female adapter with the 2 wires will power PSU #2 when PSU #1 is running or when the computer is turned on?
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Bobfantastic
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Post by Bobfantastic » Tue Feb 20, 2007 3:24 pm

If that was a question, then no and yes (in that order):
The power switches these days are momentary, so when you click it this adapter will send the 'on' signal to both supplies. If one is already on, I don't believe that it would turn on a second supply, added afterwards. But then again, you'd never turn the PC on without having everything you need plugged in, so it's probably not a problem.

Hope this makes sense.
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jhhoffma
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Post by jhhoffma » Tue Feb 20, 2007 3:24 pm

It will turn on PSU #1 and #2 at the same time.
HTPC: OrigenAE X11|Gigabyte GA-MA785GPMT-UD2H|Phenom II x3 740BE w/AC Freezer 7|150GB Velociraptor|Corsair VX450
Main: Antec 300 (SlipStream @ 800rpm/140mm @ 5v)|Asus M4A88TD-M|Phenom II x4 945 (Mugen2 pass.)|Asus EAH6850|Samsung 830 128GB|Antec TP750
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digitalfeed
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Post by digitalfeed » Tue Feb 20, 2007 4:09 pm

Awesome, thanks for the explanations everyone!
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