[Hardware issue] G5 (PowerMac11,2 DC 2.3, air cooled) random hangs

[Rui Salvaterra <rsalvaterra@gmail.com>]

Hi, guys,

I apologise in advance if this is too off-topic, it isn't directly
Debian-related (though I'm running Debian ppc64), but since a lot of
people here also have these machines, I thought about asking anyway.
Yesterday, all of a sudden, my G5 started acting up. It booted just
fine, but after a couple of minutes, sooner or later, it hanged,
windfarm blowing full blast. This happened repeatedly, until I just
gave up and shut it off. Later in the day, after work, I opened it up,
removed the dust with a blower and vacuum cleaner (I usually do it
once a year), reseated the RAM (the whole 8 x 2 GiB of unbuffered DDR2
with ECC, because why not?) and the SATA connections, but the problem
persisted. Suspecting of power delivery issues, I tried removing all
the DIMMs and leaving just 4 GiB installed, but the result was the
same (this time hanging half-way through d-i, since I was reinstalling
Debian).
This machine passed a full RAM test on ASD just over a week ago (and
another full test minus the RAM yesterday). My main suspect, at this
time, is the PSU (which is going to be a pain to remove), but I'd like
to know your opinion.

Thanks in advance,
Rui