G5 Quad CPU B heat issues

Thank you for replying. I read several reports including the site you mentioned. And I have disassembled and fixed quite a number of different Macs and other computers during the past 20 years, but I have been reluctant to go beyond the CPU front cover of the G5 quad.

So I guess there is no way around now other than to take it apart. If it's a matter of thermal past I can fix that, but I will have to mail order anything required for the LCS. I also wonder about that hex driver. If the liquid has indeed turned into gum, can this be fixed? I was wondering if it is possible to say what the most likely problem is based on my current findings, so I could check to see if I can actually get what I need before taking the system apart.

The G5 has meanwhile become so loud that I don't want to use it anymore. When I use Firebox, CPU B immediately goes to over 60 C degrees and although it goes down to 50 C quickly, the system needs alot more fan cooling than ever before. Without doing much, the fans make around 1700 rpm and the pumps around 2700 rpm.

I opened the box and noticed that the upper pump was cooler than the other. I removed all the screws as outlined in the Apple Service Manual for processor version 2. I had a bit of trouble lifting up the unit out of the box, which seemed to be stuck somewhere near the front radiator grill, perhaps the cpu contacts, but it finally came off.

There has been no visual coolant leakage. But when I shake the unit, I can here the water, which makes me wonder if there is still enough coolant inside. So perhaps the problem is that collant has evaporized. It also looks like there is almost no thermal paste between the processor and the heatsink anymore.

Several pieces of a porous black rubber band felt out of the cpu from somwhere and I don't know where it came from. The cpu's as such are movable. I'm a bit afraid not to be able to align the processor contacts propelry when putting the system back together, which could damage the pins.

Anway, I guess there is no need right now to put the system back together. I will have to check on the coolant level and apply termal paste. I have not been able to find useful details about how to refill the coolant yet.

I'm wondering what to do next. I will never buy a liquid cooled system again. Was Apple thinking that customers will trash their computers after 5 years, in particular when buying their most high end system?! Unfortunately I'm not located in the USA, and there is no Apple service provider here that I could talk to. I cannot call 1800 numbers and Apple does not have customer support contact by email.

I thought about it gain and decided not to bother with the coolant. There seems to be some room in the LCS, but the system is otherwise completely sealed, and I cannot see how coolant can possibly vaporize. I read a few more repair reports about how people refilled the coolant, but I wonder if they actually do it right. Perhaps there has to be a vacuum and even some space for the coolant to extend when it gets hot. I do not have enough information and tools to perform the coolant exchange, which is supposedly also very toxic.

I'm considering to just renew the thermal paste and then put it together again. The pins with the screws will hopefully make sure the cpu connectors slide into the box again properly. From what I can gather the G5 quad contains a better version of the LCS, but if something happened inside, which is not unlikely since the machine ran pretty much non-stop for 5 years, than more needs to be replaced than just the coolant. I'll try the thermal paste. If that does not help I will forget about it, which was a real pity though, but we'll see.

Btw, would anyone know if it was possible to put in a cpu unit from an air-cooled G5?

Yes, I have 2 pump Cooligy version, which is shown as processor 2 in the Apple service manual.

I did not speak with Apple, but I can imagine that the LCS system must not be maintained. I am certain that no coolant has leaked. I cannot look inside, so I don't know if something has clogged, corroded or broken. The iStat Pro Widget showed the same rpm for both pumps. The upper pump was cooler than the other pump when I touched it, and I cannot say if this is due to some internal problem or because of the different heat of the processors. I would probably have sleepless nights after I refilled and repaired the cooling system without really knowing if it was done correctly.

I have not seen any information that would outline a lifecycle for the liquid cooling system, but it seems now it cannot last forever. Such information was not advertised when the system was sold. I remember I was surprised when I looked inside for the first time that it actually relies exclusively on liquid cooling and has pumps. If Apple had informed me that the system will end up in the trash bin after 5 years, I would have not bought that system or pay 3500 Euro for it.

Thanks. It sounds indeed logic. I have monitored the temperatures also in the past, but never had such a difference between the CPU's and temperatures rising with the same dynamic. The temperatures as such seem reasonable, but only because the fan system kicks in heavily, making use of the system unreasonable.