# G4 power supply question



## jat (Jan 13, 2006)

I have a gigabit ethernet dual 450 and I need a power supply. Can I possibly use a PC power supply? I looked around and the price for these things is through the roof........The absolute dream would be to have someone donate a power supply if they were gettting rid of their old G4 but I don't think that's going to happen.........................any suggestions are appreciated. Thanks

Jat


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## Calgary Guru (Apr 25, 2006)

jat said:


> I have a gigabit ethernet dual 450 and I need a power supply. Can I possibly use a PC power supply?


Macs use a "soft" power supply... you can start up a mac via a USB keyboard for example. 99% of PC power supplies are the basic MANUAL type requiring the pressing of a dedicated power switch. The Mac case has a button on the front but that's NOT a mechanical power switch. If you can find the right power supply from the company that MAKES the supplies for Apple, then you've got what you need. Otherwise, you need to find the right one. There are aftermarket companies on the web offering ones with higher wattage ratings, etc. and so you don't have to get an expensive Apple part from an Apple dealer.

If it just the fan that stopped working in your power supply, it is a simple thing to just replace the fan. If it has failed completely, then you will need to replace the whole unit of course.


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## kwmike (Oct 25, 2006)

PC power supplys do not have a dedicated manual switch as far as I can see, not ATX anyway. I am going to try to power up my machine with one later tonight and I will post the results. I feel it may very well work.


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## RicktheChemist (Jul 18, 2001)

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## MacJunky (Oct 26, 2006)

http://www.outofspec.com/frankenmac/wire.shtml

I know the Sawtooth pinout is right as my Sawtooth and it's 480w ATX PSU are using it as I type this.


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## RicktheChemist (Jul 18, 2001)

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## Abysmal (Mar 14, 2005)

Actually its the 24 volts needed for the firewire and the ADC.. Right now I have a DA with a ATX supply in a Quicksilver Case.. with a modified ATX 20 Pin to 22 Pin Apple Connector..

Everything works fine, just no ADC Video power, but its a non ADC ATI AGP card so thats ok..

If anyone is interested I could dig up the link somewhere.. It was work done by a few people, but mainly from a guy calling himself the grimm ninja..

Abysmal


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## Darien Red Sox (Oct 24, 2006)

Abysmal said:


> Actually its the 24 volts needed for the firewire and the ADC.. Right now I have a DA with a ATX supply in a Quicksilver Case.. with a modified ATX 20 Pin to 22 Pin Apple Connector..
> 
> Everything works fine, just no ADC Video power, but its a non ADC ATI AGP card so thats ok..
> 
> ...


Sounds intersting, if you had the link that would be great!


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## Abysmal (Mar 14, 2005)

Here is a link to pics of my working mod up and running..
ATX PS Mods

Here is the wiring Diagram..









The original info came from this guys site.. who makes and sells them..
http://atxg4.ninjaproduction.com

Abysmal


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## krs (Mar 18, 2005)

MacJunky said:


> http://www.outofspec.com/frankenmac/wire.shtml
> 
> I know the Sawtooth pinout is right as my Sawtooth and it's 480w ATX PSU are using it as I type this.


So the Sawtooth doesn't use -5 volts and the PG output.

Do you just clip those on an ATX supply and jumper those two pins to ground and +3.3 volts respectively?

What about the output voltage tolerances, are they the same between the Sawtooth supply and the ATX one?

And I take it the connector fits.


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## Abysmal (Mar 14, 2005)

Thats right.. a sawtooth doesn't need any special rewiring.. 

My favorite trick for B & W's and sawtooths is to buy a $3.95 atx powersuply extender and rip out pin 18.. the -5 volt line.. it should be spliced to a ground but in all the years I have been doing this ( 5 plus ) I have never attached the ground to pin 18 and never had an issue..

Abysmal


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## krs (Mar 18, 2005)

What about the PG lead? 
Do you disconnect that as well or is that not necessary?
What is the PG lead anyway?


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## Abysmal (Mar 14, 2005)

krs said:


> What about the PG lead?
> Do you disconnect that as well or is that not necessary?
> What is the PG lead anyway?


Wow.. over all of the years of modding i've missed that.. 

Basiclly PG or ( PwrOK ) is the line that tels the system that the power supply is fully ready.. And when it is it is a +5V ( but could be +/- 1 volt )

This line ( pin 8 ) should be tied to the 3.3 voult line..

The really scary thing is I have re-cased/re-supplied a total of 8 machines ( 6 B & W's and 2 sawtooths ) just by clippingn the -5V line ( pin 18 ) and using a standard atx supply and never had a problem.. all machines are still up and running.. 

So I guess there is some tolerence on the macs.. time to fix a few machines

Abysmal


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## krs (Mar 18, 2005)

Al I can say is :lmao: :lmao: :lmao: :lmao: :lmao: :lmao: :lmao: :lmao:


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