Failing PowerPC system...

[Don Dutile]

Jarod Wilson wrote:
> So... I have this old dual 800MHz PowerPC system (c. 2001 "QuickSilver" Power 
> Mac G4), and its been sporadically locking up under Mac OS X lately, but to 
> date, hasn't under Linux (though it doesn't get used under Linux as often). 
> Well, tonight, I was going to use it for a PowerPC kernel build, but before 
> doing that, fired up a yum upgrade, which led to a disturbind discovery... 3 
> of the 25 or so packages to be upgraded hit cpio errors unpacking files from 
> the rpms, claiming md5sum mis-matches.
> 
> This, coupled with the lock-ups under OS X led me to try another experiment... 
> And wouldn't you know it, a repeated sha1sum on the same file only gets the 
> correct result roughly 90% of the time. To make it more interesting, I've 
> seen some of the incorrect sha1sums pop up more than once. I'm assuming I've 
> got some hardware failing here.
> 
> So anyone have suggestions for diagnosing exactly what component is starting 
> to fail? My first thought was cpu, then motherboard, and now memory... I 
> figure memory is probably the easiest place to start poking, but is there a 
> memtest86 equivalent for PowerPC? If not, I guess its memory stick roulette, 
> and on to other hardware from there. Open to any and all suggestions...
> 

Yup, try messing w/RAM modules first;  pop them out, spray the cobwebs/dust out,
and reseat the modules.  Try them in the same slots they came out of first, and
if that doesn't improve, reverse them.  if reversing is better, then remove the
2nd (or 3rd & 4th if 4-card set).
If it persists after the RAM shuffle, pull, clean-out, & reseat the disk cables.
Parallel IDE (i'm guessing with old hw) isn't the most reliable medium either.
if that doesn't work, try reseating the CPU.

in summary, interconnects are a common cause of intermittent problems seen in
an aging system.  anything you can do to 'scrub' / improve the interconnects 
will probably improve &/or solve your intermittent problems.

- Don