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The PowerMac G4 M5183 is a model in the AGP Graphic Series. All AGP Graphic Series computers including models M6921, M7232, M7824, M7825, M7827 have similar issues with similar solutions.

Note: This troubleshooting guide covers the PowerMac G4 (AGP Graphic Series).

PowerMac G4 won't turn on

Your computer will not boot.

If your computer will not turn on, you see no lights, and hear no fans blowing, first check that it is plugged into a working power outlet. Also check that the red breaker on the back panel of your computer is set to the appropriate power setting. If your computer still fails to power up, your PMU battery may be dead, you may have a bad power supply, or your logic board may need replacing.

PMU battery is dead

The Power Management Unit (PMU), manages all power usages of your computer. When the PMU battery dies, the battery needs to be replaced and the PMU board needs to be reset. To replace the PMU, see our PMU repair guide.

Bad power supply

If the computer still does not start-up after replacing the PMU battery and resetting the PMU, then you may need to replace your computer's power supply.

Bad logic board

If replacing the power supply did not fix your PowerMac's booting problem, then you will need to replace the computer's logic board.

Display is not working

Your display is black.

Bad graphics card

First check that the monitor is functional. For example: you should see a power light on the display. You should hear a normal start-up sound when you power your computer on indicating that the computer is booting but not sending a video signal to the monitor. If the display is functional and the computer boots, but you see only a black screen, you will need to replace your graphics card.

Bad logic board

If replacing the graphics card did not fix your PowerMac's booting problem, then you will need to replace the computer's logic board.

Keyboard and/or mouse doesn't work

If you have access to another computer, try plugging the keyboard or mouse into that computer to see if the keyboard and mouse are functional. If they are not functional, then replace the mouse and keyboard. Otherwise, you will need to replace the logic board on your PowerMac.

CD-DVD ROM drive problems

Your disc is not being read.

Bad Disc

If the disc is not being read or is having trouble being read, the disc may be scratched. Check the bottom of the disc for any visible scratches.

Bad CD-DVD ROM drive

If your disc is not scratched and you are still having problems, you will need to replace the CD-DVD ROM drive. Such problems include failure to open, improperly reading discs, loud clicking, and/or whirring noises.

Audio problems

If your computer's audio is not working, first check that the speakers you are using are functional (i.e. plugged in and on). Test the speakers on a system that you know works. If the speakers are functional and the computer is simply not sending an audio signal, then you will need to replace your computer's logic board.

Flashing question mark on start-up

The computer displays the flashing question mark when it can't find a bootable operating system. This could be because your OS is corrupt, the computer doesn't have enough RAM, or your hard drive is failing.

Bad operating system

Try booting off an OS CD. Run Apple's Disk Utility and try to repair the disk. You could also try Alsoft's DiskWarrior. If this fails, reinstall your operating system. If you can, erase the hard drive prior to reinstalling the OS.

Not enough RAM

This is quite rare. If you have insufficient RAM for your computer to boot the operating system, you may get the flashing question mark. Installing more RAM or downgrading to an older operating system will fix this. You need 64MB RAM to run OS 9, 128 MB RAM to run OS X 10.0-10.4, and OS X 10.5 requires 512 MB RAM.

Bad hard drive

The hard drive may have been erased, corrupted, or damaged. If the hard drive has been erased, format it as HFS+ and reinstall your operating system back onto it. If it is corrupted or damaged, you need to replace it. Failing hard drives can display intermittent data corruption prior to failing completely. They often gradually get louder and start to click. If your hard drive is making abnormal clicking noises but still works, back up your data immediately and replace the hard drive.

Fan is noisy

If your computer's fan is noisy, first try cleaning it. If cleaning the fan doesn't reduce the noise to an acceptable level, then you should replace the fan.

USB, firewire, ethernet, and/or audio ports don't work

All of the ports on the back of your PowerMac (except for the display ports) are directly connected to the logic board. If any of these ports are not working, first check that there is no debris or contaminants in the port by cleaning them out. If the port continues to malfunction, then your computer's logic board needs replacing.

The computer loses track of time

If your computer looses track of time, then the PMU battery is dead and needs replacing. The power management unit (PMU), manages all power usage of your computer and keeps track of time when the computer is unplugged. When the PMU battery dies, the battery needs to be replaced and the PMU board needs to be reset.

I turned my power Mac G4 on for the first time in 5 years. The computer started just fine, the mouse and keyboard were working just fine. After a few minutes the mouse and keyboard stopped functioning, I tried different USB ports and a different mouse with no luck. I restarted the computer and although the computer turns on, the display won’t startup and the computer starts to sound like the fan is working extra hard. I’ve restarted the computer at least three times now with similar results: no display, no start-up, and fan whirling loudly. Diagnosis?

Austin - Antwort


Well I'm a ten year old tech kid and my dad's g4 just stopped working. He hasn't used it for about a half a year and we just got a power outage about 2 weeks ago. I don't know if the power outage has anything to do with it but it was on sleep when that happend. I don't know if it needs a new PMU battery or what. maybe it just blew a fuse. I don't know. Tried unplugging and plugging back in. Tried holding down for 20 secs. It won't indicate power on the button board . He doesn't have a Apple studio display. Just a view sonic. Apple pro keyboard and Apple ball mouse. any ideas ?

Tristan - Antwort

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