The Power Macintosh G4 is series of personal desktop computers released by Apple in 1999, and sold through 2004. This page is for the M5183 designation.

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Why does this computer not power up at all?

I have replaced the pram battery, power supply, and switch on this PowerMac G4 450 Mhz dual processor computer and still no power. Will a new logic board assure a fix or could it be the computer processor, ribbon cables, etc. causing this? I don't want to sink much more into this unless it is a pretty sure fix. Thanks.

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ndwig , here is the way Apple suggest that you check this particular symptom:"

System is completely dead (no fan movement and power LED is not lit)

1. Verify the power outlet is good.

2. Replace the power cord.

3. Make sure the voltage switch on the back of the power supply is set to the correct


4. Reset the logic board. Refer to “Resetting the PMU on the Logic Board” in this


5. Check for trickle voltage on the power supply connector. Refer to “Power Supply

Verification” in this chapter. If verification fails, replace the power supply.

6. Disconnect external devices, including the monitor, and start up the computer.

7. Remove internal cards and start up the computer.

8. Disconnect internal hard drives from the logic board and start up the computer.

9. Check the modem connector. If the connector has any bent pins, replace the logic


10. Check the pins in the power supply connector on the logic board. If the pins are bent,

replace the logic board.

11. Replace the logic board.

Hope this helps, good luck.


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Thanks. I'm pretty much to the logic board part of this.



Check and see if your CPU is switched to on


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@Mason Schmidgall, how do you switch the CPU to on?


Thanks for your input. I use the power button on the front of the machine try and power it up. There was a storm that put the power off here for just a few minutes. Ever since then the computer has not responded at all.




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