Is my processor dead or is it the motherboard?

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Level 1

8 points

Is my processor dead or is it the motherboard?

My MDD dual 1.25 stopped booting. Repair guys said the PSU was dead (I tested the PSU... they were right). I bought a new one, installed it and now when I press the power button, the fans all run at top speed, but no chimes and no startup. Hard Drives don't spin up.

Also, the battery died (forgot to pull it when I removed it from AC for the repair).
Would a dead battery cause it to not start up at all?

Is there a way to tell if it's the processor card or the mother board?

Mirrored Drive Door G4 (dual 1.25ghz PPC 2GB RAM), G3,G4 Towers, B&W G3 (POS), Mac OS X (10.4.11), 2 GB RAM, Radeon 9000 Pro

Posted on Sep 6, 2009 2:19 PM

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Answer 1

Sep 6, 2009 2:52 PM in response to tom2323

Would a dead battery cause it to not start up at all?

Yes. For experimental purposes, you can pull out the battery and press the reset button \[hold for a quarter minute, release for five seconds, proceed] after each power outage/power cord removal. Convenient daily use requires a good battery.

It is very difficult to tell which is the culprit -- CPU or motherboard. But a used slower CPU can be had for under US$50, a motherboard can cost US$100.

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Answer 2

tom2323 Author

Level 1

8 points

Sep 6, 2009 3:21 PM in response to Grant Bennet-Alder

I did forget to mention that the motherboard's red light does light, and the heat sink DOES get warm fairly quickly, but neither Hard Drive spins up (5V power checks out as coming to them properly).
Is the warm heat sink possible cause to think the processors are working?

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Answer 3

Sep 6, 2009 7:31 PM in response to tom2323

Resetting the Logic Board

Resetting the logic board can resolve many system problems. Whenever you have a
unit that fails to power up, you should follow this procedure
before replacing any modules.
1 Unplug the computer.
2 Press the Power On button on the front of the unit.
3 Open the side access panel.
4 Remove the battery from the logic board.
5 Wait at least 10 minutes before replacing the battery.
6 Make sure the battery is installed in the correct +/-
direction.
7 Reassemble the computer and test the unit.

Note:
This procedure resets the computer’s PRAM. Be sure to
check the computer’s time/date and other system parameter settings

Check this site for battery part numbers and sources. Mac PRAM, NVRAM, CUDA/PMU & Battery Tutorial

 Cheers, Tom 😉

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Answer 4

Sep 6, 2009 8:47 PM in response to tom2323

The red light on the mother board is there to indicate it is getting power.

By any chance did you remove the cpu? if so pull it out and re-seat it again as I experienced similar symptoms with a cpu that had not been seated firmly (2nd hand unit). After it was firmly seated it worked.

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Answer 5

Oct 21, 2009 5:32 AM in response to tom2323

I had a similar poblem with my PM G4 FW800. I tested PSU and battery, I reseted all resetbuttons on MB. I've bought a new CPU and computer now works.
When I replaced a radiator from CPU I saw that thermopaste was like a stone (dry out) and CPU probably burned down.

P.S.
Sorry for my english, I speak a little.

Message was edited by: VladimirMsk

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Answer 6

Moof666

Level 1

107 points

Oct 21, 2009 5:15 PM in response to tom2323

"Also, the battery died" And...? Did you replace the dead battery with a good battery? If not, nothing else matters.

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