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| G5 2 GHz dual in the early 2005 dual 2.7 GHz | |
| Posted by: bengi3 on 2020-05-08 12:10:11 I have some known good early 2005 logic board but short of 2.7 GHz liquid cooled processors (I believe they are all gone by now). Is the swap of 2.0 processors feasible? | |
| Posted by: beachycove on 2020-05-08 17:59:51 As an experiment, I once successfully swapped 1.8 processors from (as I recall) a four-RAM-slot machine from 2004 into what had been a 2.0 eight-RAM-slot machine from 2003 (one of its processors was dead). The machine needed to be calibrated, which any processor swap whatsoever entails in a G5, but it worked just fine afterwards. I don't have it anymore so can't check the details, but I posted on here about it somewhere, probably about two years ago. If you search, it will come. What I don't think possible is use of the final G5 processor in the earlier machines. The earlier processors may well all be swappable -- despite what people say. You will, however, need the relevant Apple Service Diagnostics disc to do the calibration (there are two versions, one of which is specific to the very last of the G5s). Refreshed heatsink compound will work wonders, too. | |
| Posted by: bengi3 on 2020-05-08 20:27:01 yes, I am well aware of the thermal calibration having performed it several times. I have ASD for 2003, 2004 and 2005 PM G5. This time I would try to make one working G5 out of a bunch of dual 2.7 carcasses but without knowing if its the logic board or the processor that are busted I am groping in the dark. I have a working 2004 G5 2x2 GHz so I would like to do some experiments. | |
| Posted by: Franklinstein on 2020-05-08 21:20:54 I hate the Delphi LCS because it wasn't a great design in the first place and wasn't intended to be serviced, so I'd prefer to get rid of it. Some of the dual 2.5s had a Panasonic LCS and they were much better, but I didn't have any of those to swap over. Even if I did I doubt I would have done so because that system will still ultimately need maintenance that may not go well. Here's what I did with my dual 2.7: I disassembled the heatsink assemblies from a couple bad 2.0 processor modules and attached them to the 2.7 modules. I reinstalled the new air-cooled 2.7 modules and also a bodged LCS cooling pump. Why the cooling pump? Diagnostics and thermal recalibration fail on these if the LCS pump isn't running. So what I did was create a loop with the old hose, fill the pump with water, and set it out of the way as much as possible during testing. Once the pump's electrical connector was attached and the air deflector installed, I booted the Apple diagnostic disc and ran the basic suite of logic board tests to make sure everything relevant was properly recognized. Then I ran thermal calibration, which passed. After that, I shut it down, disconnected and removed the LCS pump, and closed up the case. It rebooted in OS X and has been running fine since. The fans rev up more frequently and a bit louder than they used to, but CPU temperatures are kept reasonable and there are no system errors or crashes like it used to have with the old LCS. Under normal use the computer does not miss the LCS pump. I had considered doing the same with the Quad G5, but unfortunately the 970MP runs much hotter than the 970FX so it's not a great idea. Also the air heatsink for the single dual-core 2.0 and 2.3 modules is much larger than that of the old single-core modules, so it's not possible to fit two of them in the same case. So eventually I'll have to rebuild the Quad's LCS. | |
| Posted by: bengi3 on 2020-05-09 11:30:44 Thank you Frankl, I did some experiments with a known good 2.7 logic board. The 2.0 GHz processors does work on 2.7 logic, unfortunately only one was good but the Mac needs both processors in place to power on. So I booted into open firmware and luckily I managed, before the system eventually crashed, to reboot with only one processor (for the less experts: setenv boot-arg cpus=1), see picture. Then I have a spare 2.0 GHz processor: this one has the plastic that holds the connector in black rather than the usual whitish (see picture) and while it works with the logic board of the June 2003 dual 2 GHz, is not accepted by the 2.7. I believe this is a later 2.0 model and the incompatibility can depend on a different multiplier (bus ratio). First picture: PowerMac G5 2.7 with 2.0 processors booted off only one CPU: Second and third pictures: Black connector and processor:    | |
| Posted by: bengi3 on 2020-05-10 00:22:27 Set environment command:  | |
| Posted by: demik on 2020-05-10 03:42:13 Good job ! 2.0 GHz G5 have a tendency to dies. I got a pile of them back in my lab. There is a few different 2.0 GHz models : - PowerMac7,2 (original G5) are 970 processors - PowerMac7,3 (really 2005) are in fact 970fx Processors 2.7 GHz were 970fx, If I remember correctly an early motherboard won't work with fx processors (don't quote me on this though) | |
Posted by: bengi3 on 2020-05-10 04:39:36Good job !I did check, my 2.0 GHz are all 970, none of them is FX. So far I have 5 couples of stone dead 2.7 and another bunch of dead 2.0. What a disaster has been this G5 project! | |
| Posted by: demik on 2020-05-10 05:04:37 I heard you. Out of my 8 G5 collection, 3 died because of CPU / Logic board. - One of them went through TWO logic boards and a two pairs of CPUs, dunno if that make 4 dead. - 2 Nvidia GPUs blown - Coutless of DDR sticks burned Lately one of them is becoming flaky, but seems a recap will save it. Reliability for PowerMac G5 is really bad. If you don't know, here is a good article here: https://lowendmac.com/2014/which-power-supply-works-in-my-power-mac-g5/ Most reliables here ones here are the 2005 2.3 DP and single 1.8s (HDD died, but this is ok) G5 CPUs and Logic Boards are dying left and right :/ | |
| Posted by: bengi3 on 2020-05-10 07:51:03 Anyhow: ASD says that both processors are ok, but I cannot get to load the desktop and can only boot open firmware and ASD, no OS X CD nor HD. | |
| Posted by: demik on 2020-05-10 10:36:09 Hmmm... Something fishy there. Guessing you did try with minimum RAM installed. Did you try a Linux CD ? I would guess it will fail too, but where is the interesting part. Where does Mac OS fail in verbose mode ? You can find ISO online, for example ubuntu Mate provided a Linux CD for PowerMac computers : http://cdimage.ubuntu.com/ubuntu-mate/releases/16.04/release/ | |
Posted by: bengi3 on 2020-05-10 11:25:05Hmmm... Something fishy there. Guessing you did try with minimum RAM installed. Did you try a Linux CD ? I would guess it will fail too, but where is the interesting part. Where does Mac OS fail in verbose mode ?I am running right now the ASD tests. RAM yes, two sticks 256 for a total of 512. I was thinking of trying Morphos, but will also try Linux and verbose. Will keep you posted. | |
| Posted by: bengi3 on 2020-05-10 12:51:14 Some results: ASD: all tests passed Booting in verbose mode says: overtemp signal Connceted the pump (this one in the picture is one of the LCSs that I have fixed): the boot process arrives at a blue screen but cannot get to the desktop and the fans become quiter, so I immediately powered it off. Tried again the thermal calibration but the software says that CPU 0 and CPU 1 have wrong register: I believe that the hybrid thing (7,3 logic and 7,2 processors) is not a good idea.     | |
| Posted by: demik on 2020-05-10 14:53:17 Yep, looks like OS X is trying to set Fan/Something speed and fails because there is no case in the kext for this. You are using non-fx processors on a PowerMac7,3 motherboard, correct ? | |
Posted by: bengi3 on 2020-05-10 21:12:01Yep, looks like OS X is trying to set Fan/Something speed and fails because there is no case in the kext for this.Yes, infact when it stals the fans get quiter | |
| Posted by: bengi3 on 2020-05-11 05:07:55 Incidentally, I have another G5, a June 2004, which is a 7,3 but has two 2.0 GHz 970 not fx | |
Posted by: demik on 2020-05-12 02:09:07Incidentally, I have another G5, a June 2004, which is a 7,3 but has two 2.0 GHz 970 not fxInteresting… | |
| Posted by: demik on 2020-05-12 12:16:15 Just an idea : is the OpenFirmware version the same ? | |
| Posted by: bengi3 on 2020-05-14 13:26:23 Found another dead G5, this time the processors were ok, so I fixed my original 2.7. Processors air cooled modification followed by calibration with the pump connected. is it now safe to remove the pump? I am not so sure.  | |
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