Welcome to the MacNN Forums.

Westbo · Nov 9, 2011, 11:48 AM

Hi all,

I am unable to start my G5 (late 2004)

I have reset the SMU, which previously worked with the G5 starting and restarting for a few days. However more recently, I am unable to start up, hearing only the fan and an inconsistent "modulation" noise of what I guess is the processor attempting to start.

Resetting the SMU does not seem to have any affect. Occasionally after successive "modulations", the chimes will ring followed by a very slow boot up which freezes with the apple logo on a gray screen.

After several attempts of force quittiing, resetting the SMU and starting, may I get lucky, but more often not. I am sometimes able to start the G5, hearing chimes immediately followed by a successful boot. Restarts are usually unsuccessful.

So, whats going or not going on?

Thx for your help.

Power Mac G5 2 Ghz OSX 10.4.11

reader50 · Nov 9, 2011, 02:49 PM

Check the battery. Your Mac is over 5 years old, and the battery is an easy replacement. At the very least, pull it and measure the voltage.

Big Mac · Nov 9, 2011, 02:59 PM

That sounds like a processor problem to me, unfortunately.

Westbo · Nov 9, 2011, 04:46 PM

Thx reader50, I'll check the battery. Big Mac, I was able to boot then restart from the hardware test disk.
Running the extended test, the logic board has following error detected:

***ERROR*CODE***ERROR*CODE***
212C/1/1: 0x00000096

***ERROR*CODE***ERROR*CODE***

Thx guys.

reader50 · Nov 9, 2011, 04:53 PM

Beware that the logic board test will sometimes flag problems with peripherals. ie - if the hard drive is bad, the test may think the SATA controller is bad. A bad RAM stick can also make the system flakey.

Make sure it has a good battery. Then unplug all outside peripherals except keyboard, mouse, and monitor. Then boot from DVD and rerun the tests.

Assuming it still fails, unplug the hard drive and boot from DVD. Repeat tests. Still fails? If you have more than one pair of RAM sticks, test it one pair at a time. Note that RAM slots should be populated from inner pair outwards - your manual will have the details.

Westbo · Nov 9, 2011, 05:00 PM

No peripherals have been attached. Just a monitor, keyboard and mouse. I'll follow up on your recommendations and let you know.

Thx!!!

Waragainstsleep · Nov 9, 2011, 09:55 PM

I don't recognise that error code. They usually have CPU in them somewhere if its a CPU. I'd go to an Apple Store and ask there, they can look them up. I don't have access any more.

Westbo · Nov 11, 2011, 05:27 PM

Hi all

Follow Up... I replaced the battery and restarted several times from the hardware test CD. Each timeI ran the extended test with the HD removed and with memory removed and swapped in pairs. Same error. I also ran the hardware tests from TechTool 4 which the processor, and memory passed.

reader50 · Nov 11, 2011, 07:55 PM

Logic board after all. Ugh. Well, it was worth a shot. Unless someone has another idea ...

Waragainstsleep · Nov 11, 2011, 09:01 PM

Those boards are quite cheap on eBay these days. Pain to swap out though.

Westbo · Nov 12, 2011, 06:39 AM

Hokay... Guess I'll go shopping. What would be a fair price? Waragainstsleep, how much of a pain to swap it out? Are there directions to be had that I can download?

Waragainstsleep · Nov 12, 2011, 10:40 AM

They seem to be around $100 on eBay. The trick will be getting the correct one.

If you can find a service manual for it you'll see how its done. I notice ifixit doesn't have a guide for doing logic boards in these though. Some of the eBay boards come with manuals.