Question (Can/how) do you wire multiple power supplies?

Jan 16, 2022
Hello I could use some advice for using more than one power supply to power car amplifiers and Virtual pinball solenoids and knockers.
I have a few 300/350w ATX power supplies that I would like to use for this setup.
I have them all wired so I can turn them on with a switch. Obviously just one of the 4 pin plugs won't have the ability to carry the amperage the the Amplifiers will draw. So I have read that combining ALL the 4 pin plugs will help with available amps on that line.
SO 2 questions..
First is : Does a 300 watt power supply have 300w available to ALL voltages? 3.3v 5v. & 12v? So if all the 12v was combined there would be 300w @ 12vdc (roughly 25A)...
Second: Can I take 2 power supplies and combine ALL the 12v pos. & neg. together? Rather than having one "dedicated" power supply for amplifiers. then 2nd for other stuff, when there may be unused power still available from the first power supply.


What make and model PSUs? Quality and efficiency matter. A labeled 300 watt PSU will not deliver 300 watts.

And the connectivity used (series, parallel) could easily lead to dangerous conditions.

Start with the following link within this Forum:

Then sketch out ( a schematic) how you plan to make the actual connections.

Include the devices (you mentioned amplifiers and solenoids) in your schematic.

Are you using the PSUs in two projects: car speakers and some sort of pinball machine. Not sure about the requirement for physical devices in a virtual machine - more explanation needed.

Overall, what you have in mind is not likely to end well.
Jan 16, 2022
In General what they are powering is kind of irrelevant.
The main thing is will 2 power supplies connected in parallel (wired in series the voltage will go up) across the 12v lines of each 4 pin plug Be okay? The end goal is to have a larger amount of amperage than if I used one power supply. After that the power will go through a fuse/distribution block and out to the individual devices, what ever they may be. Consider that they MAY be higher current circuits.
One PSU had a label with some info I will check tomorrow when back in shop.