Finally, positive results to report in this epic battle.
I did a full tear down of the Quad once again, followed by a complete disassembly and thorough cleaning of the two CPU cooling pads, then rebuilding of the cooling loop, refilling it and then reassembly back into the Quad… and it worked! It finally worked! I dubbed the new cooling loop FrankenCooler Rev 4. Here is a photo of it, ready for reassembly into the Quad:
The thoroughly cleaned CPU cooling pads, plus the careful design and construction of FrankenCooler Rev 4 (no kinks, no leaks, only one fill/bleed line and over 250 ml of coolant forced into the loop) finally did the trick.
CPU A now idles in the high 30 C area, a drop of 15-20 C over previous values, and CPU B, until now the "problem child", now idles in the high 40s C, again a drop of 15-20 C. This is an excellent result; I am very pleased with it.
The coolant I used is XSPC’s EC6 Blood Red, 1 Liter bottle. I chose this vibrant color to provide maximum visibility of coolant flow, and critically, leaks. Here is a photo of the coolant used:
As you can see from the earlier photo of FrankenCooler Rev 4, the process of filling the loop and killing a few small leaks spattered red coolant all over the towel I was working on.
When it was all said and done, here are the iStatMenus readings for CPU temps and fan speeds (I let the Quad run for a while until I was sure that these were stable values):
As you can see, fan speeds are still a little higher than I would like, but they are well within my acceptable range from an audible perspective.
Because I haven’t seen similar photos here on MacRumors, following are photos of the CPU cooling pads teardown. First, the CPU A cooling pad extracted from the LCS:
Next, the same cooling pad with the heat sink removed from it, exposing the microchannels underneath. These channels circulate coolant evenly across the entire CPU heat spreader, transferring heat from the heat spreader to the coolant. That heat is then carried by the cooling loop to the radiator, where fan forced air extracts it and directs it out of the Quad’s case.
Finally, a photo of the two CPU cooling pads fully disassembled and before cleaning (I used a toothbrush and an exacto knife blade to meticulously clean each of the microchannel grooves.
Getting to this result with FrankenCooler Rev 4 was not without its challenges – Murphy
never takes a holiday. It was CPU B’s cooling pad and micro channel guide that I
really wanted to get to and thoroughly clean/flush. Guess which set of cooling pad screws would not budge, and started to strip the heads as I tried to turn them? You got it - CPU B! The “fun” just never ends on this task!
In an effort to overcome this new obstacle, I sprayed just a little bit of WD-40 onto the two screws that wouldn’t budge. WD-40 is reputed to be a “penetrating lubricant”, so with any luck, it would loosen things up a wee bit. Regrettably, it did not - no impact at all.
After watching multiple YouTube videos on the best ways to free up seized screws, I tried out each of the techniques I had seen. They all looked so easy and so effective on YouTube! But all too predictably, none of them worked… until the very last one which directed that if all else fails, drill out the screws. All else
had failed, so I got out my electric drill and drilled out each of the two screws. With some effort, this eventually succeeded.
Of course, drilling out the screws destroyed both the screws and the threads they screwed into:
so I had to hunt down a nut and bolt arrangement to replace the two destroyed screws. Happily, I have a large stash of such things, and I was able to find two that fit.
There was more “fun” along the way, but in the interests of not writing a book here, I will skip further details – the end result was successful.
I would declare complete victory except that after reassembly into the Quad I noticed a new small coolant leak coming from the pump housing itself. At present, I have no means of correcting this, so my newly cool Quad has only a limited lease on life before enough coolant is lost from this new leak to render the LCS inoperative again. As I said before, the fun never ends on this task. The one saving grace here is that FrankenCooler Rev 4 retains its fill/bleed line, which is about 5 inches long, is filled with coolant and is clamped off at the very end. This is thus a form of coolant reservoir that will be able to replace coolant lost to the pump leak for a time, until it too is exhausted. For now, I have placed an absorbent pad under the cooler to sop up any coolant that leaks.
I will take apart the burnt-out pump from my other Quad and examine it carefully, to see if there is anything I can learn from it and apply to the FrankenCooler Rev 4 pump leak.
...and, since my other Quad
is crippled by its burnt-out pump, I am going to try my hand at air cooling it. That will be a whole new adventure, but somehow this new adventure feels easier than the LCS approach. I will likely take a break and work on some other things before tackling the air cooling project. I am sure that it will be as all consuming as this current LCS project was.
For now however, I will savor the sweet taste of success after two months of incredibly frustrating work.
I have been documenting and photographing what I am doing all along. I am now about half way through writing a comprehensive guide to LCS reconditioning, covering the entire process from "you have an overheating Quad" to "your Quad is now properly cooled and working well" - tools, procedure steps, tips and tricks and LOTS of photos - pictures really are worth a thousand words. There probably will be "a thousand words" of course; by now it must be clear to you all that I am one of those people who prefer more words to fewer. Exhaustive documentation is of far more use than sketchy documentation!
When this guide is done, I will publish it to both my
Quadras, Cubes and G5s WordPress blog and my
www.retro-computing.com blog. I will publish a link here to both when done.
To all of you who have offered your thoughts, critical commentary and advice, thank you very, very much! I would never have gotten to this point without your help! You are SO appreciated!
