Can PSU's be combined to make one higher amperage supply?

[Bert Milner]

I know I'm a little guy among giants, but I have a poor man's question.

I have two old power supplies, a 220W and something marked 300W that may have been designed for Sun Sparc station. The 300W supply doesn't have a motherboard connector I can use.

Instead of explaining all the old ATA drives, SATA drives, USB drives, and DVD writers I have hooked to my motherboard, let me just ask a theoretical question.

Can I hook the two supplies together to make one higher amperage supply?

Now before you think I'm some kind of nut that will have one of the supplies just laying there on my desk with wires running into a computer be advised: I keep this computer under my desk so nobody will see this monstrosity but me. :rolleyes:

Can I simply crimp the red to the red, ect, ect? Do I need to use rectifiers to prevent feedback from one supply to the other?

Come on now, most of you guys have expensive computer stuff still working perfectly (video cards, motherboards, memory) just sitting around doing nothing just because something faster came out. I have old PSU's.

Forgive me if this was explained elsewhere, I did read lots of stickys, did some searching and didn't find anything, but this is a big place.

- Bert

[Travis]

You can't bridge the output rails. However +12V and +5V load can be devided between the two PSUs so you have the 300W powering some components and 220W powering other components. Bridge the PS-ON# signal.

[Bert Milner]

I've tried disconnecting all drives, USB devices, all memory except for one DIMM, and the 220W PS doesn't appear to have enough power to run the motherboard. The board comes up, motherboard LED on, CPU fan on, then three seconds later everything cuts off.

I have already tried putting all the drives on the 300W and running the motherboard only from the 220W but that failed as explained above.

I need to bridge the voltages I have from the 300W supply to the voltages on the motherboard cable thats mounted on the 220W supply. But from what you said that's not possible, correct?

[Travis]

Maybe something's wrong with the 220W's PWR_OK signal. Make sure the 220W is healthy, bridge their PS_ON signal, use the 300W to power up the motherboard, use the 220W to power others including the drives.

[Bert Milner]

The 300W supply doesn't have a motherboard connector I can use. This supply has PWK_OK jumpered to run the drives. If the power needs to be synchronized then I can bridge the PWR_OK signals from the two supplies together. What I was doing is turning on the 300W applying power to the drives first, then switching on power to the motherboard.

My question was around connecting the output of the two PSU's together to increase amperage. You said simply they can't be bridged. I just didn't know if you were taking into account putting diodes inline with the voltages from both supplies to keep them isolated. Maybe the regulation wouldn't work with the diodes? Is that what you mean?

[Travis]

There'll be significant heat dissipation on the diode and you'll have load balancing issues.

[Bert Milner]

Thank you - I believe that has convinced me to not waste any more time on this project.

I do appreciate the assistance!

- Bert