Powermac G5 Quad: Overtemp + Checkstop

[robduckyworth]

I recently acquired a faulty powermac G5 (the things a beauty, even if its broken )

the problem with it is that these two lights come on, and the fans go crazy. Apparently it boots up occasionally, but i dont want to risk it, its definitely not running right. I mean, i hear the boot chime, but i havent got a hard drive in it so it isnt gonna boot.

i realise this problem could be one of two things: the logic board or the processor, is faulty. but ive been reading up on it and some people have experienced their coolant "gumming up" in the liquid cooled system. (ive cleaned most of the fans extensively and they are all spinning).

so do you reckon i should remove the processor, check for leaks and replace the coolant? or should i just strip the thing out and salvage whats left of it, and build a PC inside it?

cheers.

 

[chscag]

Sounds like fun. You might hang on a bit and wait for Harry or Nick to reply. They both have experience with working on that machine. Don't salvage it out yet.

 

[harryb2448]

It may well be a beauty but a useless beauty if she won't boot and is dead!

What are the specs of the G5 as there are numerous models. Quad Core 2.7 and 2.4 Dual Cores late 2005 are both liquid cooled using coolant similar to your motor vehicle, and a leak spells death of logic board and processors alas! First question is the perspex wind deflector in position when you remove the side cover? If not this will cause precisely the problem you describe Ron. The if it is a Dual Core have a look at this link for LED diagnosis:-

http://support.apple.com/kb/HT2652?viewlocale=en_US

Keep us posted?

 

[robduckyworth]

Sounds like fun. You might hang on a bit and wait for Harry or Nick to reply. They both have experience with working on that machine. Don't salvage it out yet.

i agree, my reason for buying it would be as a fun project

for some reason the apple support site is down atm.

ive always placed the wind deflector back on before booting, so its not that.

its a late 05 quad core powermac, with 8gb RAM.

(ive tried rearranging the ram into the correct matched slots and so on so im happy it isnt a ram issue.)

it also looks normal under the "G5" cover: cant see any leakage on the outside. so if there is a leak im guessing it would be internal.

ive already looked up the lights, they mean "CPU Hang" and "CPU overtemp". both indicate replacing the processor or logicboard as the remedies (as the last resort). the thing is - it does boot sometimes, and every time i turn it on i hear the chime, so im thinking its the processor overheating. i dunno. ive also cleared all the fans out. there was a load of gunk in there.

ill upload some photos soon and show you the inside. its a good looking machine, picked it up cheap, now just to get it to do something

appreciate the help for this btw guys.

 

[robduckyworth]

pics

 

[harryb2448]

Sure sounds like a leak destroying the CPU. Ask baggss how he got on with his:-

 

[robduckyworth]

okay cheers, will do!

 

[robduckyworth]

if i were to take the processor apart, what would be the tell tale signs of a coolant leak on the cpu?

 

[harryb2448]

Have a look at this Rob:-


PowerMac G5 Coolant Leaks/Repairs

 

[baggss]

Mine never showed any signs of coolant leak, otherwise I would have followed the above advice. Over the years of having the heat issue I would occasional lay the machine on its side or upside down immediately after shutting it down looking for a coolant leak I could point out to the Apple folks. Nothing. That's what leads me to believe it was either a paste issue on CPU A or a clog in CPU A's cooling loop.

I suppose I could still call Apple and complain about the issue. Maybe I could get a new MAcPro out of the deal!

 

[robduckyworth]

Have a look at this Rob:-


PowerMac G5 Coolant Leaks/Repairs

wow, now thats some serious leakage.

baggss, what do you mean by paste issue, the thermal grease applied to the top of the CPU?

hopefully some time next week i will have enough time to get the LCS+CPU off. ill keep you updated with what i find, im half expecting there to be a massive rusty lump of metal behind it. im fingers crossed its not, but i really am expecting it now. while i havent had "puddles of coolant" like described in the link above, im still thinking theres something bad behind there.

cheers

 

[baggss]

baggss, what do you mean by paste issue, the thermal grease applied to the top of the CPU?

Yes. There have been issues in the past with this on same Apple models, although not the PM G5s that I know of. I'll eventually take mine apart and see as well. I wonder if once I get it broken down and see whats there if I can still hit Apple up on it if was a coolant leak.

 

[robduckyworth]

if you get extremely lucky, they might

haha i doubt apple would pay for mine. i have no original discs for it and the serial number isn't registered to me. i dont think it had applecare on it otherwise when the previous owner rang up they wouldnt have told him it would be 600 to fix.

 

[robduckyworth]

right i have got the video card, all fans, speaker, and half the LCU mounting bolts off (the rest are extremely hard to get to, had to saw an allen key to size to actually get it into the area to unscrew. apple really didnt want you to mess with it.the amount of "warranty pins" on this thing is ridiculous.

 

[robduckyworth]

right just got the CPU off, still no evidence of any water spillage! the motherboard must be faulty.

 

[baggss]

right just got the CPU off, still no evidence of any water spillage! the motherboard must be faulty.

Were there any clogs in the cooling pumps, or did you even open them up?

Post some pics of the CPUs if you can.

 

[robduckyworth]

theres absolutely no evidence of spillage: no corrosion anywhere, not even on the power supply, or motherboard. i have completely stripped everything, nothing there. its so wierd!

to be honest, think im wasting my time trying to repair it. its a very strange problem, and i think ill just build a PC inside it. it would still be interesting to know exactly what went wrong though.

 

[baggss]

The pics aren't coming thru...

 

[robduckyworth]

ah how annoying. literally there was nothing wrong with it. took the cpu completely apart, the thermal grease was normal, no corrosion anywhere. must have been a clogged up pipe somewhere. its going in the bin now!

 

[harryb2448]

Hard luck Rob. Personally if you want a G5, look for the 2.3GHz Dual Core which are normal air cooling. Before you toss it, I have a service manual in CD format sitting on my desk. If it is any good, PM me and I will mail it over with my compliments.