Power Mac G5 Blue screen on start up

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chrismay105 Author

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Power Mac G5 Blue screen on start up

Hi (My first post)

18 years owning Macs and this is the first time I need some advice...

I have an old G5 Power Mac (OS 10.5.8) that has been playing up for a few months.

Blue screens, wierd jaggedy start up wheels (See photo) and then the screen goes black.

About 3 weeks ago I put in a new battery (half size AA - same as original) and that seemed to give it a new lease of life. But tonight its gone bad. Blue screen flashes the mouse on and off, can start up in safe mode (could before). Used it last night and it was fine.

Really confused. Can't afford a new one but don't know where to begin to get this sorted.

Any advice would be great!

Thanks

Chris

PowerMac, Mac OS X (10.5.8)

Posted on Jan 26, 2012 12:58 PM

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Answer 1

Best reply

BDAqua

Level 10

238,961 points

Jan 26, 2012 1:17 PM in response to chrismay105

Hi Chris,

Since it starts in Safe Mode it easily could be the Video Card, Quartz is turned off in Safe mode.

Boot off your *original* G5 Install Disk while holding down Option/alt key to select AHT, then run the extended Apple Hardware Test.

Have you blown the dust out of it lately, especially the Video card?

Get Temperature Monitor to see if it's heat related...

http://www.macupdate.com/info.php/id/12381/temperature-monitor

iStat Menus...

http://bjango.com/mac/istatmenus/

And/or iStat Pro...

http://www.islayer.com/apps/istatpro/

If you have any temps in the 70°C/160°F range, that's likely it.

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Answer 2

chrismay105 Author

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Jan 26, 2012 1:22 PM in response to BDAqua

Thanks BD. I was mean't to type Can't start in safe mode... Any advice?

Cheers

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Answer 3

BDAqua

Level 10

238,961 points

Jan 26, 2012 1:30 PM in response to chrismay105

Can it boot from the Install Disc?

1. Insert the Mac OS X Install disc, then restart the computer while holding the C key.

2. When your computer finishes starting up from the disc, choose Disk Utility from the Installer menu at the top of the screen. (In Mac OS X 10.4 or later, you must select your language first.)

Important: Do not click Continue in the first screen of the Installer. If you do, you must restart from the disc again to access Disk Utility.

3. Click the First Aid tab.

4. Select your Mac OS X volume.

5. Click Repair. Disk Utility checks and repairs the disk."

http://docs.info.apple.com/article.html?artnum=106214

Does it boot into any of these modes?

Holding Option/alt key at bootup.

Holding SHIFT key at bootup.

Target mode...

http://support.apple.com/kb/HT1661

Does it boot to Single User Mode, CMD+s keys at bootup, if so try...

/sbin/fsck -fy

Repeat until it shows no errors fixed.

(Space between fsck AND -fy important).

Resolve startup issues and perform disk maintenance with Disk Utility and fsck...

http://docs.info.apple.com/article.html?artnum=106214

We might get clues with verbose mode...

http://support.apple.com/kb/HT1492

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Answer 4

chrismay105 Author

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Jan 26, 2012 1:47 PM in response to BDAqua

OK. Doing the Single User Mode check now.

Fan is starting to get louder but its telling me Macintosh HD appears to be ok.

What do I do next? How do I get out of this DOS mode? Fan is mega loud now...

Cheers

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Answer 5

BDAqua

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238,961 points

Jan 26, 2012 1:51 PM in response to chrismay105

Don't worry about the fans, but try typing mac-boot, or shutdown -now

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Answer 6

chrismay105 Author

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Jan 26, 2012 1:54 PM in response to BDAqua

I was worried about the fans. Typed in exit...

Now I have a screen flashing between blue and black with some words that appear on the black screen that I can't read as it flashes back to the blue screen. Man this is confusing. The arrow appears for a second on the bluescreen...

What should I do BD?

By the way, you are a legend for helping me out!

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Answer 7

BDAqua

Level 10

238,961 points

Jan 26, 2012 2:06 PM in response to chrismay105

It sounds like the Video card, but let it cool down for 30 minutes & see if Option key on power up works.

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