Thank you for being a valued part of the CNET community. As of December 1, 2020, the forums are in read-only format. In early 2021, CNET Forums will no longer be available. We are grateful for the participation and advice you have provided to one another over the years.

Thanks,

CNET Support

Question

iMac G5 Blue Screen woes

Jul 26, 2011 3:54PM PDT

My iMac G5 (20", 1.5 GB RAM) has the dreaded blue screen on startup. I have searched the archives without finding anything to throw light on identifying the issue.

I have spent four days on this problem and reinstalled the system (both A&I and clean install) several times. The most significant fault finding/eliminating includes:
-run Disk Utility to repair permissions & repair disk (no disk errors)
-zapped PRAM & replaced battery
-erased & zeroed internal drive and reinstalled Mac OS X 10.4
-run Apple Hardware Test (no problems reported including memory)
-removed each memory array & rebooted
-swapped memory arrays in slots (no change)
-tried booting with & without mouse & keyboard (keyboard is faulty)
-booted with different keyboard & mouse
-reset PMU/SMU (I think)
-restarted in Safe Boot mode and ran without issues (able to update OS and other software to current latest versions using System Updater & internet)
-used as target disk for G4 host PPC (ran as expected)

Problem still persists. Whenever I boot into 'normal' mode I get the blue screen. I assume it is a hardware issue and the normal boot process hangs when it gets to a process/address/peripheral that is not active during Safe Boot.

My question - how do I determine which component has the fault or is it time to bite the bullet and take it to a tech? (I did take it to the Apple Genius Bar and he guessed the HD was probably failing but it runs for hours when booted into Safe Boot mode).

Discussion is locked

- Collapse -
Answer
Could that be one of the G5 series that
Jul 26, 2011 11:01PM PDT

suffered from a whole slew of bad capacitors?

- Collapse -
Answer
Video card
Jul 26, 2011 11:04PM PDT

I can almost guarantee you it's the video card. Had an iMac that would do something similar once. Worked fine in safe mode, but you try and boot it normally and it'd either stall loading Finder or the video would be all garbled.

Safe boot disables hardware acceleration, so all graphics are done by the CPU instead of the GPU.

Of course since it's an iMac G5 we're dealing with, you can't rule out the possibility of bad caps either. That's quite a bit less likely given it works in safe boot, but it's still quite possible that this is at least a contributing factor.

Now, the fun part is, Apple's retail stores are going to claim they're not trained on systems that old, so you'll have to take it to an AASP in the area to get an estimate to fix. The other kicker is that the system may have passed into Apple's Vintage status, which means that it's been more than 5 years since that specific model was discontinued. If you happen to live in California, then you get an extra 2 years before it hits Obsolete status and no one can get parts. However, given the age, it's probably not worth repairing even if you can get the parts. Just making an educated guess, I'd say probably somewhere around 150USD for the video card, then another 100USD for labor give or take. That's probably more than the thing is worth if it were in perfect working order. If it were me, I'd just put the money towards a new iMac or whatever else you may want to get.

- Collapse -
Checked capacitors and no obvious problem
Aug 2, 2011 4:04PM PDT
Confused I eventually got around to checking the capacitors in the G5 iMac and there is none that is obviously defective and no bulging. Everything looks pristine on the inside.
At this stage I am stumped and not keen on spending any more money on a machine this old because I also have a laser printer that is playing up and a new fusing assembly just cost me $AUST 225.00 (and I am not sure that is the problem there either). Probably should have stumped up for a new laser printer.
Thanks to mrmacfixit, Jimmy G. and Bob for your suggestions. Looks like the G5 will get parked in a cupboard until some computer tech owes me enough of a favour to try another hard drive in there (I can't get it to boot from an external HD).

regards,
Darryl
- Collapse -
Answer
Top two ansers are
Jul 27, 2011 6:05AM PDT

Noted at https://discussions.apple.com/thread/2773393?threadID=2773393&tstart=1

1. BAD CAPS (see google for details and pictures.

What criteria to use? PERFECTION. No corrosion, No domes, No leaking fluid, No blown bottoms, No white crusty unidentifiable residues, in other words, PERFECTION.

2. Hard drive.

Now there are folk that can't accept item 2 because it ran in safe mode and passes all tests. But those folk tend to pay full price at the shop.
Bob