Actually got powerpc Mac, and dual-core G5 at 2.0 Ghz at that! Updated Leopard install, installed Powerfox, now compiling ppcports - libgcc14 (it will take a while..).
So far machine seems to be quiet and stable, temps under load hover near 60 C for CPU and 58-64 for GPU and mem controller.
I control it via RealVnc from Android, but display works too, just not at 1440*900. Lets see if posting works ...
Happines was short lived bevause at around 9AM localtime I wake up to unusual loud fan noise ... screen was frozen. I powered machine off, and then it come back ... with three beeps/flashes! ( I checked other threads, this seems to be memory issue).
I opened up case, removed fancy transparent door, removed fan assembly, replaced cr2032 (old one was reading 2.9 V), re-seated ram (two sticks in innermost slots, not really matched but it was working ok for 30 hours, many of them at 100% load compiling stuff!). Put all case elements back ... same error.
Replaced two ram sticks with two other ddr2 (4200) sticks from PC - now no beeps but no chime either. Tried various ram combinations .. Powermac correctly detects ram sticks installed in wrong slots, so at lest SMC is working? I tried to reset it by pusing little button at the bottom edge of logicboard - it sadly did not help.
I suspect there was power failure - my much newer PC handled it fine, but older machines probably more sensitive to those issues (I already got strange no bios issue on my older PC motherboard with Athlon x2 3800).
Eh .. If ussue will mot resolve itself magically I think I am out of luck... GPU was sitting firmly in place held by its little pcie slot arm - so I did not removed it completely, but I have no other ppc mac compatible gpu, so even if it was "just" GPU it will take some more time until I find/create some replacement.
I am afraid cpu itself or logicboard can be damaged now - but all ways to test this a bit too complicated for visually impaired me (I see bigger components ok with my glasses, but small components .. I really need some unusual close up to see them. Also, no long screwdrivers for cpu heatsink disassembly! Ok, should be fixable by visiting home hardware store ..)
Well, it still fun to tinker with, but I wish those pro workstations had a bit more verbose bootup diag .... (I got service manual describing 7 leds on motherboard. But from my understanding for seeing some of them light up you need to run machine with its case open, and I am a bit reluctant to do this in case overheating will add more damage ...)
EDIT: turned machine on with transparent plastic cover removed.
Strange, aren't fans suppose to go into overdrive in this case? in my case they stayed quiet but spinning.
Yellow led and one above it (3, 4) were illuminated, leds 1 or 7 not. So if I read manual correctly this means main voltage is ok? And cpu also at least sensed?
May be I should wait for longer to see if led #5 ("open firmware arrived") comes on?