The Quad G5 is one of the better ones in this regard and most of the ones that would have suffered early deaths already have, but it still requires service due to evaporative losses and sediment, and any Quad on its original processors is by now almost certainly a windtunnel under load. An ailing LCS, even an intact one, runs the real risk of an unexpected shutdown if the CPU it can no longer cool effectively ends up exceeding its internal thermal limits; you'll see a red OVERTEMP light illuminate on the logic board when this is imminent, followed by a CHECKSTOP. Like an automotive radiator it is possible to open the LCS up and flush the coolant (and potentially service the pumps), but this is not a trivial process. Additionally, those instructions are for the single-pump Delphi version 1 assembly, which is the more reliable of the two; the less reliable double-pump Cooligy version 2 assemblies are even harder to work on.
Unfortunately our current employment situation requires I downsize, so I've been starting on consolidating or finding homes for excess spare systems. I had several spare Quad G5 systems in storage in various states, all version 2 Cooligy LCSes, but the only LCS assemblies I have in stock (and the LCS in my original Quad G5) are version 1. These LCSes were bought Apple Certified Refurbished, so they were known to be in good condition and ready to go; as the spare Quads were all on their original marginal LCSes and processors, I figured I would simply "upgrade" the best-condition v2 G5 with a v1 assembly. The G5 service manual doesn't say anything about this, though it has nothing in it indicating that they aren't interchangeable, or that they need different logic boards or ROMs, and now having done it I can attest that it "just works." So here's a few things to watch out for.
Both the v1 and the v2 assemblies have multiple sets of screws: four "captive" (not really) float plate screws, six processor mount screws, four terminal assembly screws (all of which require a 3mm flathead hex driver), and four captive ballheads (4mm ballhead hex). Here's the v1, again:
Once installed, the grey inlet frame used in the v2 doesn't grip the v1:
The fan and pump connector cable is also the same between v1 and v2, though you may need to move the cable around a bit to get the halves to connect if it was in a wacky location.
Now run thermal calibration, and enjoy your renewed Apple PowerPC tank.
Hi! I've got an iMac G5 20" Model A1145 (iSight) which symptoms look as you describe (the fans never ramp up, then occurs an abrupt shutdown above a certain temperature).
ReplyDeleteAs I've been using it exclusively as a high-level alarm clock for years now, I'm a bit reluctant to disassemble that compact beast... ;-)
I sometimes have opened it a few times though (last time was to replace the power supply) and there's no obvious sign of leakage, from what I was able to see.
Do you think a change of thermal paste could be enough? (if I ever have the courage to disassemble it...)
iMac G5s are all air-cooled, so it's possible cleaning out and replacing the thermal paste might be sufficient. But you point out the worst thing about the iMac G5: they are a pain to work on.
DeleteI'm surprised: aren't those copper tubes carrying fluid?
Deletehttps://guide-images.cdn.ifixit.com/igi/Qfp1MOBfgUNsecKL.huge
If it's just a piece of metal carrying heat to another point in the computer, it's probably the worst design ever... ;-)
They do have liquid in them, but heatpipes aren't considered "liquid cooling systems" because the fluid is sealed in them and the heat diffuses passively through to the heat exchanger through vapour-liquid transition rather than using an active pump to move the hot liquid around.
DeleteThanks a lot for the explanation! :-)
DeleteI still use my PPC 1.8 ghz air cooled tower for a variety of tasks. Personally I prefer the air cooled to the liquid cooled PPC. Maybe my Mac isn't as fast but the machine runs 24/7 and gives me little or few issues to complain about. (and I've never had or will have a leak!) Just my 2 cents . . .
ReplyDeleteI forgot to mention my 1.8 ghz is a DP model!
DeleteFYI, RenéRebe upgraded a single socket G5 to a air cooled 2,5GHz CPU:
ReplyDeletehttps://twitter.com/ReneRebeTM/status/1167837104824639489
Maybe a LCS is not needed anymore.
Single socket, though. Not sure how well that would work for the Quad.
DeleteThe Quad runs fine with one CPU removed and doesn't even balk at the lack of an LCS. As long as you install CPU A back in the same slot it was in to start with you don't even need to run a thermal calibration. I know from experience, I also use my G5 for development and have even added an NVMe SSD and Radeon HD6670 which are both supported under Linux and don't cause issues in OS X other than sleep not working.
DeleteThat's not what I meant. One CPU is obviously a lot cooler running than two.
DeleteOf course. The air cooler that ships with single socket machines occupies more than half of the space that the LCS does so you'd have to get creative in order to air cool both CPUs. I reckon a couple of Noctua heatsinks would probably do the job if you could figure out how to mount them.
DeleteCK - Have wondered if it might be possible to put an M.2 / MVME upgrade card into that 8X slot? While you'd obviously have to find one with auto-trim (garbage collection) and might need to do some testing, I wonder if you might really open-up that G5's Hyper-Transport with such a system disc? They really cheap (the cards anyway). https://www.ebay.com/itm/143180485808
ReplyDeleteYes, but it only works in Linux because Leopard has no support for NVMe in the kernel. Bearing in mind it's PCIe 1.0 and most SSDs are only x4 the performance isn't amazing but it definitely speeds up my compile times.
DeleteIf you want the fastest possible storage for OS X then you should consider something like the Sonnet Tempo SSD which lets you add two additional internal SATA SSDs in RAID and works from 10.4 onwards.
DeleteHey @classishasclass are you still in possession of a v1 LCS that you are willing to part with for $? I know it has been a couple months since this post!
ReplyDeleteI appreciate the thought but I'm hanging on to them for now since I want to keep my G5 running. Might see when we get our new place, though.
DeleteI appreciate the reply. Found 2 g5 systems locally and had no idea one was a quad until I got it home. I have a 2.3 dual air cooled as well, but only PCI-x and AGP, no PCI-e. On the quad, one of the CPU's runs great at 33c degrees at idle, however CPUB is at 60c-70c at idle. So that causes typical Jet engine noises. But I won't run it for more than a couple minutes as to no degrade the CPUB card.
DeleteDefinitely keep that DP 2.3, they're good systems. On the Quad that does seem like a serious range difference between them. I wonder if there's something up with the CPU B mounting to the heatsink if CPU A is nice and cool.
DeleteThat's my thinking! gonna follow the disassembly guide from your 2014 post and the apple service manual. Thankfully I have the long t-handle hex drivers from replacing my mac pro CPU's. Thanks again for the reply.
DeleteUnfortunately no change. My true thought is that if the loops are connected or separate, the sludge or build up has gone into the cpub water block. Since CPUB would be the bottom cpu. Probably just time to find a replacement LCS or rebuild this one entirely... not sure if the cooling system would respond well to that.
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