cjtmacclassic
Well-known member
Hello all,
I've had this early '05 G5 2.7 marinating for a number of years. I worked up the motivation to revive it recently, but found that the LCS had done exactly what anyone would expect. Despite my best efforts, I couldn't revive either of the CPUs. Thoroughly encrusted.
Rather than try to find an exact CPU match on ebay in working condition (ha), and thus continue to operate a leak prone cooling system, I chose to do something different, but worse.
I spent some time comparing the motherboards and CPUs of the G5 family. I needed to find a motherboard that possessed:
1. The same ports and port arrangement
2. The same (dual) CPUs, but in a more tame, air cooled 2.0 or 2.3GHz configuration
3. Support for whatever flavor of PCI the G5's stock graphics card is. I tried to understand PCIx, but it just gave me pain.
Items 1 and 2 are purely mechanical. You could certainly opt for a single CPU configuration, but I haven't taken apart enough Powermacs to determine if there are differences in screw standoff/thread locations; It's entirely possible some may not be there at all, which would compromise CPU mounting and motherboard fitment.
The donor I chose was an absolutely wrecked June '03 dual 2.0. $40. No RAM, no graphics, no hard drive. I already have these, and simply needed the motherboard and CPUs within.
I gutted the LCS, CPUs and motherboard from the 2.7 and did the same on the donor. During disassembly, I found no real difference in the construction of the housing save for one mounting pin, which isn't crucial, but you can tell it's unpopulated.
I found that the power supplies share the same apple part number, and just kept the one I already had installed in the former LCS machine. The housings do have different P/Ns, but are entirely compatible for the purposes of this downgrade.
In addition, I found that all the accessory components (cpu fans, speakerfan, airflow cover) fit without issue.
Post swap, everything looked fine. No mechanical issues mounting two air cooled G5s and their motherboard in place of two liquid cooled G5s.
Upon attempting to start up, I got two clicks as the power supply faulted. I attempted to trace the problem and disconnected everything but the bare minimum needed to run the motherboard. Two clicks, an audible arc, and a faint wisp of smoke from the topmost CPU. In my rush to assemble this, I hadn't carefully examined the CPUs.
I found electrolytic fluid from the twelve 100uf/16v aluminum caps on both CPU cards. One CPU was obviously spent and had a scorch mark below this International Rectifier component I haven't googled. The other, while leaking, hadn't yet immolated and I cleaned it thoroughly.
I cautiously reassembled and attached the cleaned, unburned CPU card in slot 0 and was pleased to find this machine is perfectly content to chug along with a lobotomy.
notes:
I have two more G5 2.0s on order. I'm also getting some very squat electrolytic caps that I hope match the footprint limitations and exist in quantities greater than 10 without a 43 week lead time. I realize cleaning the goo is only a temporary measure and that the caps are very much falling out of spec, and intend to recap this. The spare CPUs are for when I screw up.
I would suggest taking a look at your G5's CPU card. They may be reaching the age where recapping is as much a necessity as it is on a beige Mac. Mine set itself on fire, ymmv.
I've had this early '05 G5 2.7 marinating for a number of years. I worked up the motivation to revive it recently, but found that the LCS had done exactly what anyone would expect. Despite my best efforts, I couldn't revive either of the CPUs. Thoroughly encrusted.
Rather than try to find an exact CPU match on ebay in working condition (ha), and thus continue to operate a leak prone cooling system, I chose to do something different, but worse.
I spent some time comparing the motherboards and CPUs of the G5 family. I needed to find a motherboard that possessed:
1. The same ports and port arrangement
2. The same (dual) CPUs, but in a more tame, air cooled 2.0 or 2.3GHz configuration
3. Support for whatever flavor of PCI the G5's stock graphics card is. I tried to understand PCIx, but it just gave me pain.
Items 1 and 2 are purely mechanical. You could certainly opt for a single CPU configuration, but I haven't taken apart enough Powermacs to determine if there are differences in screw standoff/thread locations; It's entirely possible some may not be there at all, which would compromise CPU mounting and motherboard fitment.
The donor I chose was an absolutely wrecked June '03 dual 2.0. $40. No RAM, no graphics, no hard drive. I already have these, and simply needed the motherboard and CPUs within.
I gutted the LCS, CPUs and motherboard from the 2.7 and did the same on the donor. During disassembly, I found no real difference in the construction of the housing save for one mounting pin, which isn't crucial, but you can tell it's unpopulated.
I found that the power supplies share the same apple part number, and just kept the one I already had installed in the former LCS machine. The housings do have different P/Ns, but are entirely compatible for the purposes of this downgrade.
In addition, I found that all the accessory components (cpu fans, speakerfan, airflow cover) fit without issue.
Post swap, everything looked fine. No mechanical issues mounting two air cooled G5s and their motherboard in place of two liquid cooled G5s.
Upon attempting to start up, I got two clicks as the power supply faulted. I attempted to trace the problem and disconnected everything but the bare minimum needed to run the motherboard. Two clicks, an audible arc, and a faint wisp of smoke from the topmost CPU. In my rush to assemble this, I hadn't carefully examined the CPUs.
I found electrolytic fluid from the twelve 100uf/16v aluminum caps on both CPU cards. One CPU was obviously spent and had a scorch mark below this International Rectifier component I haven't googled. The other, while leaking, hadn't yet immolated and I cleaned it thoroughly.
I cautiously reassembled and attached the cleaned, unburned CPU card in slot 0 and was pleased to find this machine is perfectly content to chug along with a lobotomy.
notes:
I have two more G5 2.0s on order. I'm also getting some very squat electrolytic caps that I hope match the footprint limitations and exist in quantities greater than 10 without a 43 week lead time. I realize cleaning the goo is only a temporary measure and that the caps are very much falling out of spec, and intend to recap this. The spare CPUs are for when I screw up.
I would suggest taking a look at your G5's CPU card. They may be reaching the age where recapping is as much a necessity as it is on a beige Mac. Mine set itself on fire, ymmv.