View Full Version : G4 Won't Boot.

Nov 11, 2005, 11:39 PM

I have a G4 that wont boot, when I first bought it absolutley nothing would happen, so I was told that the PSU was faulty.

I have pulled the PSU out and connected up one I pulled from one of my working beige machines, now some lights flash (burner, zip and a little red led on the logic board next to the last peice of ram) and the fan begins to spin but stops dead after about 5 secs.

Do you guys have any ideas that I could try now?


Nov 12, 2005, 03:56 PM
Do you have the specs of the G4? Done any aftermarket upgrades? (Powerlogix, Sonnet, etc)

Nov 12, 2005, 04:00 PM
Does it POST?

Nov 12, 2005, 04:02 PM
you need a power supply for your model or at least one with all the same pin outs.

Nov 12, 2005, 04:27 PM
Hi Guys,

It is a sawtooth g4 400Mhz which was upgraded to dual 500Hmz official apple not third party.

If it is showing some for of life now does it mean that it is definitley a PSU related problem and the logic board is in the clear?

It is the d55 labelled led next to the last ram stick that illuminates when the power button is pressed.


Nov 13, 2005, 05:53 PM

Nov 14, 2005, 11:32 AM
Does it POST?

Again.. does it POST?
(Power On Self Test) Do you hear a chime at boot?

As noted, you should probably attempt to use the same power supply. And I would sugggest putting the original CPU back in as well, until you get it working normally. THEN try swapping in the OEM CPU upgrade.

Nov 15, 2005, 04:58 AM
Hi Mate,

Sorry I wasn't sure what POST meant. But in answer to that, no it does not. Just the lights fflash then nothing.

I don't have the original CPU either.

Nov 15, 2005, 09:16 AM
If it doesn't POST, assuming the internal speaker works, then you have some fairly serious problems.

Either the power supply is incorrect, the RAM is bad/incorrect/needs to be reseated, or more likely, the CPU isn't seated correctly.

You may want to try a CUDA reset after you've verified that the CPU is correctly installed and there's thermal gel between them. Also, you should check out
http:://xlr8yourmac.com for word on whether your PSU is correct or the source of your woes.