Reuse G5 power mac psu?

[minihack]

I believe that going the other way for the G5 power supply use is actually a bit more complex.
The G5 power supply needs different feedback from the motherboard so as to keep it on and has somewhat different control signals.

Compare the above with the standard ATX supply pinouts:

For instance, one of the things is that 5v sense voltage in the first picture - this is a voltage I think from an internal loop generated in the motherboard and fedback to the supply. If that voltage is not sensed then the power supply shuts down. Also, you'll need to do a lot of re-wiring to make the outputs fit the standard pattern of ATX supplies - probably end up spending more on connectors and wires than a reasonable ATX supply would cost. The wiring may easily end up looking a little over the top.

Good luck.

 

[MyG5]

... For instance, one of the things is that 5v sense voltage in the first picture - this is a voltage I think from an internal loop generated in the motherboard and fedback to the supply. If that voltage is not sensed then the power supply shuts down...

Thanks. I think this will be a show stopper for me, end of story.
Agree with the cost bit - initial intent was just trying to use as many original components as reasonably feasible, for a hobby G5 hack. More difficult than I thought. (PS: Just for curiosity, pin#20 has "-5V" in the ATX figure shown. I take a look at Newegg and Amazon and it appears that most of the commercial ATX supplies do not have a negative -5V explicitly listed. Interesting.)

 

[windi]

You would spend a lot of time rewiring the original PSU cables to correct pin outs, not to mention they're too short so you'd have to obtain longer cables somehow anyway. It would make it more original yes and you could run the original HDD and DVD power cables using the original black cable and holder. But that might be useless too if your motherboard is in the way of the cables.

To save time I did it like this:

If you have a new PSU that has large fan in the bottom (not rear) then the heat sinks of the PSU are low enough to fit in the original PSU case without cutting any holes. The only hole I had to cut was enlargening the hole where cables come out. The extra wires of standard ATX power supply were useful though as I had 3 hard disks (two 2.5" ones in single 3.5" adapter) and some molex eating fans and case lights. The soldering necessary was connecting the both orignal PSU fans to the fan cable, and connecting the original apple wall power connector (gotta be very careful with insulation there.)

The two small fans look small after ripping out a 120mm fan, but in my experience they created enough air flow to keep the PSU cool to the hand and there has not been problems in few weeks of usage. PSU I used had integrated fan speed controller so it kept them quiet, but the fans are extremely loud at full 12V. So if your PSU doesn't adjust the voltage nicely you have to add your own resistor or RPM controller or maybe swap them to more quiet fans. Some people have cut a large hole to the top of the PSU case for a big fan, but I didn't want to go for that because it'd mean cutting the decoration plate which covers the PSU making it look clean and shiny through the original plastic window in the side.

Have to agree about the original fans, they were all more or less loud except the PSU fans which were OK at low voltage and didn't require any odd 4-5 pin connections. G5 can be 8 years old so I guess it's a lot for the fans which Apple used. Maybe Mac Pro cases have more quiet or more durable fans?

 

[patriciooholegu]

Actually it can be done, and is easy:
https://www.tonymacx86.com/threads/guide-acbel-1kw-psu-to-atx-success.202668/