PowerMac G5 - Dead?

[thatsteve]

Hello folks. My G5 tower (dual 2.5, liquid cooled, 7GB RAM, 2x300GB HDD, 2x23" Apple displays) appears to have died. I fired it up last night for the first time in a few weeks (have more or less fully migrated my photography workflow to my MBP over last couple of months) to pull off and archive a bunch of stuff spread over the 2 drives in the tower. Turned out there was around 500GB of stuff to archive, so I set it to dumping to an external disc and left it running over night. All finished when I checked this morning (although I noticed the activity light on the external drive still blinking). Satisfied that everything had transferred ok I restarted the machine to freshen it up and now it's dead!

At first, the POST chimed but then nothing happened for a few minutes until the fans then go into overdrive but now there's no chime and the power LED doesn't stay lit. I've pulled the RAM to see if maybe a stick had gone bad but no change. I've held the PMU reset button but no change. Any ideas of what I could do next?

I'm a little bit pissed off about this but not too upset. I've never completely trusted this machine, it's done some "weird" stuff in the past and the fans always run really loud, which I've sorta concluded may be linked to the liquid cooling, which I think is buggered. If it's dead I'll be kinda pleased to see the back of it. I was intending to run it as a light video production suite but I'll be happier to pick up a dual 2.3 for that as I much more trust the reliability of the air cooled machines.

 

[Byrd]

Sounds like the LCS has failed (ie. pump, liquid dried up, leaking) based on your past reports of high fan speeds. Try lying the G5 on it's side, the liquid might have dried up and this might move around what is left in the tubes to get it going for a little while. Also remove "G5" cover and check for leaks. Ideally you need to rebuild the LCS and you're pretty lucky it has stayed running up to now with heavy use.

Also double check RAM placement - matched going "outwards" in the slots (starting in the middle)

 

[thatsteve]

Yup, I'm coming to the same conclusion; LCS dead. Everything points to it, not least of all the peculiar gurgling sound it made when I laid the tower on its side and booted yesterday afternoon...

Oh well. I'm not going to muck around trying to refurb it, it looks overly complicated and not foolproof so I'll just strip it for parts and toss the carcass. Bummer, but I'll pick up an air-cooled G5 soon enough!

 

[beachycove]

I'd either fix it (not especially challenging, in fact), or else keep the case and buy a bashed dual 2.3 unit for peanuts.

 

[uniserver]

if its leaked… find where its leaking… should be tell tale….

fill it with what ever goes in there… then chop off the bad part/connection, use a hose clamp and be off!

i wouldn't give up before you even start…

 

[max1zzz]

You can always do what i did with mine, remove the lcs and put in air cooled heatsinks

There pretty much drop in replacements to the lcs apart from drilling out the mounting holes a little

Then you don't have to worry about that darn LCS leaking again...

 

[thatsteve]

Hmmm... That sounds doable. Could you point me at the specific heat sink you used please, and what's involved in fitting other than modifying the mounting holes? Thermal paste?

 

[max1zzz]

Something like this would do: http://www.ebay.co.uk/itm/330862268131 (i won a pair of 1.8ghz modules for £10)

you need to remove the old cpu's and drill out the mounting holes with a 6.5 / 7 mm bit (double cheack that, i may be wrong there), you may need to countersink the holes so the mounts go in easier when your refitting the modules

thern it's pretty simple, just clean and add new paste to your old cpu cards and screw them on

The only modification needed is drilling out the holes, apart fromt hat they pretty much fit right in

 

[Byrd]

The question on everyones lips reading this thread: how are the temps? I have a G5 Quad that could do with some treatment, but I'm more tempted to rebuild the LCS (as I've been into watercooling overclocked PCs) and make sure it's reliable for a few more years.

 

[beachycove]

I'd say that air cooling a dual 2.5 that was meant to be liquid cooled is a recipe for ramping up your fans, with yet more frustration with the machine looming down the road. Getting the cooling right is key to having a G5 that is pleasant to use. Mine (5, believe it or not) run quietly and stably, but my experience is that ALL G5s these days benefit from servicing. You need to freshen the heatsink paste, apart from anything else.

The failed liquid cooled machines can often be rehabilitated, though since the coolant is corrosive things can have gone too far. Having said that, I think that overhauling the plumbing would be an interesting project. You can hardly make it worse, can you?

 

[max1zzz]

Well i don't know what my orig temps where, but cpu b's cpu temp seems ok 45C at idle, 55 - 65C under high load

cpu a on the otherhand seems pretty warm, at 65 - 70C all the time. it never goes below that (but never gets any higher either)

I need to pull out cpu A'a module and repaste it (i'm sure i have either too much to too little)

I'll also add that it dosen't really ramp the fans up any more than i rember it doing with liquid cooling

 

[uniserver]

that sounds like my north bridge, in my mac pro.

anyone know why its at 164 degrees?

[attachment=0]Screen Shot 2013-12-30 at 7.44.23 AM.png[/attachment]

 

[beachycove]

Well i don't know what my orig temps where, but cpu b's cpu temp seems ok 45C at idle, 55 - 65C under high load ... cpu a on the otherhand seems pretty warm, at 65 - 70C all the time...

That's actually not bad. 40 C at idle and 55-60 C under load would be the broad targets, and one CPU will typically run a little hotter than the other.

If you can get CPU A down into a similar range as CPU B, then the hack works 100%. On the other hand, as things stand, 70 C is nearing the maximum tolerance, which is somewhere in the region of 80 C or 180 F. It'd be worth applying new paste and maybe running a thermal recalibration.