Regular readers of these forums will know that I have been working and working and working on the cooling systems of two Power Mac G5 Quads, trying to restore them to the point where their fans no longer roar like the backside of a jet engine. The first Quad was treated to an extensive, exhaustive and frequently frustrating (but ultimately successful) LCS overhaul. The second was converted to Air Cooling. As I reported in another thread about the "cost" of this work, along the way I "fried" both CPU cards in one of the Quads, and damaged one CPU card in the other. I ended up with one air cooled "half Quad" (only one CPU card in operation, the other turned off to avoid the video artifacts it causes) and one totally dead LCS-cooled Quad. I tallied the "cost" of my cooling work at 3 of 4 CPU cards, or 75% loss.
Today, I am pleased to report that the cost has dropped to 50%. I have always had trouble believing that I fried both CPU cards in the LCS Quad. @amishallin reported how they had removed one CPU card from their Quad and it ran just fine. I decided to try the same thing on my LCS Quad. Perhaps one of those two cards was alive, a fact that was being masked by the one that was dead. Perhaps...
I disassembled the LCS Quad yet again (seemingly for the millionth time!), removed the CPU B card (the one closest to the bottom) and reassembled. My plan was to test first with CPU B removed, and if that didn't run, reverse the CPU card removal, removing the existing CPU A card and putting the CPU B card into its place. In essence, test it with one CPU only, first using CPU A and then using CPU B. Assuming that Murphy would be hard at work (after all, he has dogged this entire effort, all the way through!), my guess was that the first test with CPU A only would fail, and I would have to disassemble the Quad again, swap the CPU B card into the A slot and try over. Only after this maximum amount of effort did I hope that it might chime and boot again.
Well... Murphy must have been "asleep at the switch" today. After I removed CPU B and reassembled, the machine chimed and booted right up! It runs a little warmer than my Air Quad, idling in the 48 C area. During boot, I observed it to peak at 75 C.
But it runs! This intrepid Quad simply refused to die. It has life once more, and courtesy of the quiet fans I put into it, the noise level is dramatically reduced and quite acceptable. Mac OS X believes it is spinning the intake fans at about 2400 RPM, but I have those fans now wired through a controller card that presents external dials for adjustment of speed. I can directly control the speed of both the intake and exhaust fans now, all of which have had their stock Apple parts replaced with new, quieter ones.
So, I now have two "half Quads", one liquid cooled and one air cooled, both fully operational and more than acceptably quiet. I could combine them and get one full Quad, but instead I will stay on the hunt for additional Quad CPU cards and expand both to full Quad status when i get them. I would rather have two operational half Quads than one full Quad.
Today, I am pleased to report that the cost has dropped to 50%. I have always had trouble believing that I fried both CPU cards in the LCS Quad. @amishallin reported how they had removed one CPU card from their Quad and it ran just fine. I decided to try the same thing on my LCS Quad. Perhaps one of those two cards was alive, a fact that was being masked by the one that was dead. Perhaps...
I disassembled the LCS Quad yet again (seemingly for the millionth time!), removed the CPU B card (the one closest to the bottom) and reassembled. My plan was to test first with CPU B removed, and if that didn't run, reverse the CPU card removal, removing the existing CPU A card and putting the CPU B card into its place. In essence, test it with one CPU only, first using CPU A and then using CPU B. Assuming that Murphy would be hard at work (after all, he has dogged this entire effort, all the way through!), my guess was that the first test with CPU A only would fail, and I would have to disassemble the Quad again, swap the CPU B card into the A slot and try over. Only after this maximum amount of effort did I hope that it might chime and boot again.
Well... Murphy must have been "asleep at the switch" today. After I removed CPU B and reassembled, the machine chimed and booted right up! It runs a little warmer than my Air Quad, idling in the 48 C area. During boot, I observed it to peak at 75 C.
But it runs! This intrepid Quad simply refused to die. It has life once more, and courtesy of the quiet fans I put into it, the noise level is dramatically reduced and quite acceptable. Mac OS X believes it is spinning the intake fans at about 2400 RPM, but I have those fans now wired through a controller card that presents external dials for adjustment of speed. I can directly control the speed of both the intake and exhaust fans now, all of which have had their stock Apple parts replaced with new, quieter ones.
So, I now have two "half Quads", one liquid cooled and one air cooled, both fully operational and more than acceptably quiet. I could combine them and get one full Quad, but instead I will stay on the hunt for additional Quad CPU cards and expand both to full Quad status when i get them. I would rather have two operational half Quads than one full Quad.
