Double atx power supplies safe?

Thread Starter

Sulvek

Joined Aug 27, 2022
25
I just saw one of these on amazon while browsing unrelated products. I have a slew of low watt PSUs about and got the idea of adding a couple 300w to get a 600w dual setup. This screams as unsafe to me. Just because a product exists does not mean it should. Can anyone shed light if this is safe or not? Also can you explain in detail why it is safe or unsafe? Thank you very much.
 

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panic mode

Joined Oct 10, 2011
2,715
looks cheesy to me. paralleling sources can work but it is often problematic. primary issue as already mentioned is fault mode. and problems do happen with one or another connection having poor contact etc. and if there is even slight difference in resistance among any of the circuits, creating imbalance and as everyone knows current will favor one path over another. then you get chain effect where most stressed connection fails and after that it is like dominos, problem repeats itself (faster and faster) until other connections are down.
 

Thread Starter

Sulvek

Joined Aug 27, 2022
25
looks cheesy to me. paralleling sources can work but it is often problematic. primary issue as already mentioned is fault mode. and problems do happen with one or another connection having poor contact etc. and if there is even slight difference in resistance among any of the circuits, creating imbalance and as everyone knows current will favor one path over another. then you get chain effect where most stressed connection fails and after that it is like dominos, problem repeats itself (faster and faster) until other connections are down.
Is there any safety concern with trying this on a low end build? Any way this could create a fire?
 

panic mode

Joined Oct 10, 2011
2,715
possibly, this does add more contact points and each of them is possible point of failure.
years ago i tried passing high current through bunch of pins of stacking header. at first it looked like all is great but after couple of months it became a sobering experience - few units got quite charred at the mentioned connector even though applied current was well bellow simple sum of individual ampacities of paralleled pins ;)
 

crutschow

Joined Mar 14, 2008
34,285
The problem is balancing the load currents between the two units.
The one with the slightly higher output voltage will tend to hog all the current, which may cause it to overheat.
A small series resistor in each output will help with that, but that will reduce the regulation accuracy and add some power dissipation in the resistors.
 

bassbindevil

Joined Jan 23, 2014
824
If your main load is a graphics card with separate power connection, maybe you can run that off one supply and the motherboard/CPU off the other one. Just tie the commons together. But, power supplies are cheap now... do you really need to pinch pennies on the thing that is the foundation of your computer build?
 

NigelPearson

Joined Oct 28, 2022
1
As a way to double the output of cheap PSUs, it is unsafe.
Two motorbikes don't add up to a car?
Two children does not make an adult!!!

As a way to give redundancy (i.e. keep PC working if one PSU fails),
it might have potential, if it had some diodes between each PSU and the load?
(of course, the PSUs would need their output increased by the diode drop voltage)
 
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