Heikki Lindholm

Q: Working on the G5 quad liquid cooling system

I have a G5 quad with the one pump Delphi LCS ("version 1"). I'm guessing the LCS is clogged because when the machine sits idle (even in reduced CPU setting, which cuts the GHz in half), the fans and the pump slowly, over several hours, go to full speed. Temperatures of CPU B, particularly the second core, shoot to near 100C when loading the CPUs. ASD 2.6.3 usually passes, but sometimes ends in checkstop and overtemp. A local mac service center, which I had the machine checked at (in hopes of getting free repairs because of a leak), said it's fine.

 

As a simple first measure, I tried replacing the thermal paste on the CPUs, with little effect. The LCS didn't seem to be leaking or corroded anywhere, but when handling it, it sometimes made a bubbling noise, so, there's probably air in there. I thought I'd take the LCS apart next, but before that I have some questions which I hope someone can answer.

 

Which one, the upper or lower, is CPU A and which is B? I've read the machine runs on one CPU just fine, but which one?

 

If I switch the CPUs the other way around and later switch back, does something in the nvram reset so that thermal calibration needs to be run? I'd rather not run it as it seems to have mixed success.

 

What material/size are the CPU block O-rings on this system?

 

If I use a vacuum pump on the service valve (I gather it's of the "r134a high" type(?)), what would be a safe level of vacuum? Has anyone tried using the manual brake kits, or car cooling system refill kits that use compressed air and venturi valves, on the LCS?

 

I suppose I'm just going to try attaching a hose as a reservoir to the service valve and fill through that first, but if that doesn't bring satisfactory results, I'll level-up to some sort of vacuum method.

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Posted on Sep 17, 2011 11:59 PM

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Q: Working on the G5 quad liquid cooling system

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  • by japamac,

    japamac japamac Jan 27, 2012 4:48 PM in response to Ramón G Castañeda
    Level 7 (24,390 points)
    Jan 27, 2012 4:48 PM in response to Ramón G Castañeda
  • by Chris323i,

    Chris323i Chris323i Jan 27, 2012 5:02 PM in response to japamac
    Level 1 (0 points)
    Jan 27, 2012 5:02 PM in response to japamac

    Ah yes. I remember explaining that issue to them. A cousin of mine actually had flickering and whatnot so he had his card replaced by Apple. However, my MBP never had strange flickering or any obvious tell-tale signs of a failing GPU. My MBP would have trouble starting up occassionally. Then it progressively got worse to where the computer would only turn on when it was very cold. Then it reached a point where it would only chime, leaving me with a black screen. The service techs were never able to get the MBP to turn on so they just replaced the logic board. Problem solved.

  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda Jan 28, 2012 1:00 AM in response to japamac
    Level 4 (1,468 points)
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    Jan 28, 2012 1:00 AM in response to japamac

    japamac wrote:

     

    On the MacBook?    Really?

    http://www.tuaw.com/2011/03/08/have-a-macbook-pro-with-a-faulty-gpu-and-no-apple care-you-may-s/

     

    Thanks, but that's not what I have.  I have a plain vanilla MacBook, not Pro, and it has the Intel GMA 950 display… with a whopping 64 MB of shared system memory.  

     

    Message was edited by: Ramón G Castañeda

  • by Heikki Lindholm,

    Heikki Lindholm Heikki Lindholm Jan 28, 2012 1:23 AM in response to Ramón G Castañeda
    Level 1 (135 points)
    Jan 28, 2012 1:23 AM in response to Ramón G Castañeda

    Going OT here, but... These older macbooks had generous amounts of thermal paste applied. Really generous. Mine was overheating and producing an awful smell of burnt something. I opened it to find...generous amounts of thermal paste. Replaced the paste with a saner amount and cleaned out dust. Now it works nicely, and the temps went down 10 C or so iirc. I also had to throw out a bulging battery and now run the thing without one.

  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda Jan 28, 2012 1:39 AM in response to Heikki Lindholm
    Level 4 (1,468 points)
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    Jan 28, 2012 1:39 AM in response to Heikki Lindholm

    Heikki Lindholm wrote:

     

    …I also had to throw out a bulging battery and now run the thing without one.

     

    Yes, I did that for a while too, until I found the $30 replacement battery at amazon.com.

  • by Chris323i,

    Chris323i Chris323i Feb 4, 2012 8:54 PM in response to Ramón G Castañeda
    Level 1 (0 points)
    Feb 4, 2012 8:54 PM in response to Ramón G Castañeda

    Just wanted to give you all an update. I was able to order all the new tubing, clamps, coolant, and thermal compound that Heikki recommended on his site from Sidewinder.

    I have just finished draining the coolant and do not like what I see. In the pictures, you can see that the coolant was changed by Apple in the revision of the system. The fluid is still water-like in its viscocity and has the signature "fishy" anti-freeze smell. I drained almost 200mL. Unfortunately, as you can see, there was particulate matter that also removed from the system. The clear/yellowish bits are probably from the sealer/adhesive connection around the tubing but the red and black matter are from the inside of the system. I plan to use Prestone radiator flush clean the aluminum components and discarc the rubber plastic tubing.

     

    /___sbsstatic___/migration-images/175/17502669-1.jpg

     

    /___sbsstatic___/migration-images/175/17502669-2.jpg

     

     

    I found it interesting that Apple used this very elastic tubing inside these flexible plastic hosing bits found on the underside of the radiator.

    /___sbsstatic___/migration-images/175/17502669-3.jpg

     

     

    I also found it interesting that Apple essentially sealed off these aluminum ports found on the topside of the radiator but still used a heavy amount of sealant around them and capped them off with rubber caps.

    /___sbsstatic___/migration-images/175/17502669-4.jpg

  • by BDAqua,

    BDAqua BDAqua Feb 4, 2012 9:25 PM in response to Chris323i
    Level 10 (123,765 points)
    Feb 4, 2012 9:25 PM in response to Chris323i

    Great post, thanks!

  • by Heikki Lindholm,

    Heikki Lindholm Heikki Lindholm Feb 4, 2012 11:13 PM in response to Chris323i
    Level 1 (135 points)
    Feb 4, 2012 11:13 PM in response to Chris323i

    I'd expect the black bits to be corrosion products from the CPU blocks. In the version 2 LCS, the copper blocks are not plated as they are in the ver 1 LCS. The coolant is probably not the same also because of this. Vinegar should help with the CPU blocks, but since they can't be opened, it can take some time. For the aluminum rad, the most important factor seemed to be heat, e.g. boiled water, not chemicals. I'd apply heat with the Prestone as well.

     

    The CPU blocks need to be able to move a bit to properly seat the cards (and the MB), hence the elastic tubing I suppose. A very short piece of the heavier hose might not give in much. You don't want the blocks to be so stiff that the CPUs either don't seat the MB anymore or rip the MB CPU connectors off when seated.

     

    I'd replace the aluminum ports/stubs on the rad with valved ports for easier maintenance in the future and for much easier refill/bleeding.

  • by Chris323i,

    Chris323i Chris323i Feb 10, 2012 9:50 PM in response to Heikki Lindholm
    Level 1 (0 points)
    Feb 10, 2012 9:50 PM in response to Heikki Lindholm

    Finished attaching the hoses. 1/4" ID hoses are vinyl with the larger 3/8" ID hoses being Tygon. I went ahead and added RTV water pump sealant to all tubing connections similar to what Apple had done with the epoxy. I know it wasn't necessary but I'd like to have that extra bit of assurance in the back of my head. I still need small clamps for the copper blocks but that's really about it. I'm waiting the designated 24 hours for the sealant to cure before I fill it back up with fluid.

    I went to my local Lowes and I was unable to find a bleeder valve similar to what you had Heikki. The closest thing I was able to find were some 3/8" ID fuel shut-off switches in the lawn mower department of all areas. I had to saw off the two ports at the top of the radiator to attach these switches with more vinyl tubing.

    Also, if it hasn't been noted before, the radiator is closed off into two separate systems which explains why I had to use two switches. I guess this makes sense since the upper processor would overheat much quicker once the coolant level dropped (which seems to be the main culprit of the overheating issue since I wasn't able to extract much more sediment with several subsequent flushes with boiling water).

     

    /___sbsstatic___/migration-images/175/17561276-1.jpg

  • by BDAqua,

    BDAqua BDAqua Feb 10, 2012 9:58 PM in response to Chris323i
    Level 10 (123,765 points)
    Feb 10, 2012 9:58 PM in response to Chris323i

    Impressive, thanks for the post!

  • by Heikki Lindholm,

    Heikki Lindholm Heikki Lindholm Feb 10, 2012 11:24 PM in response to Chris323i
    Level 1 (135 points)
    Feb 10, 2012 11:24 PM in response to Chris323i

    Nice work and good info, Chris. As for the r134a valves and adapters the version 1 LCS uses, they are specialised equipment and only found from air conditioning service equipment suppliers. They are overpriced and overspecced for the job. I'm sure Apple/Delphi used them, because the A/C service stations have them and are a good fit for purging/filling the LCS. Lacking such service station, they are of no benefit for the DIYer.

     

    Home improvement stores probably won't carry much good stuff for the LCS project. I shopped most items from hydraulics suppliers (like a local Parker Store). They usually have variety of connectors and valves as well as good quality hoses. The lawn mower fuel valves look like a good idea, and not costing an arm and leg as well.

     

    Just for the record, I used black rubber hose because (1) opaque hose prevents algae growth and "seeing" the bubbles/coolant is of no benefit; the pump noise is a better indicator of air and (2) heated coolant makes plastic tubes leach plasticizers which form a film everywhere. The rubber hose also seemed to create much tighter seal with the barbs than PVC. PVC especially, once removed and reapplied to a connector, doesn't work very well as it deforms from the first application.

  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda Feb 11, 2012 1:49 AM in response to Heikki Lindholm
    Level 4 (1,468 points)
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    Feb 11, 2012 1:49 AM in response to Heikki Lindholm

    Thank you for sharing your most valuable insights, Heikki.

     

    Reading about your project(s), however, leaves me with the certainty that all that would be well beyond my capabilities, as I'm all thumbs when it comes to work like that, and my old-geezer hands not that steady.  It would be great if you or anyone else could share some leads into where one might find a technician willing to do this kind of refurbishing of the LCS.  Cost becomes secondary when you are as committed as I am to the G5 Quad on account of my absolute need for the Classic environment.

  • by Heikki Lindholm,

    Heikki Lindholm Heikki Lindholm Feb 11, 2012 2:40 AM in response to Ramón G Castañeda
    Level 1 (135 points)
    Feb 11, 2012 2:40 AM in response to Ramón G Castañeda

    Ramón, about having someone do these sort of overhauls: I was actually playing with the thought that I could start doing these on the side, but there's very little demand here where I live. A few years ago, I remember seeing an Australian Apple service tech advertising that they can repair the LCS. Generally, anyone handy enough to do car maintenance can probably do the overhaul, but of course, experience of having done it before, and the proper tools, will help. One problem I see with DIY repairs is that the "pool" of spare parts gets smaller and smaller as parts get destroyed by the inevitable oopses of the DIYers.

     

    As to my approach, I'm too nitpicky and, apparently, had too much time on my hands. Unlike current electronics, water cooling isn't really black magic; if it was, cars would be blowing up all around, central heating wouldn't work, and so on. Careful material selection and as-clean-as-possible process should give a larger maintenance interval, but that's about it. Off-the-bat duct tape methods can give results that work just fine. For example, tap water is always said to be a big no-no in water cooling because of its impurities, but one guy ran a WC loop with tap water for almost a year with little ill effects.

  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda Feb 11, 2012 4:33 PM in response to Heikki Lindholm
    Level 4 (1,468 points)
    Desktops
    Feb 11, 2012 4:33 PM in response to Heikki Lindholm

    Heikki Lindholm wrote:

     

    …Generally, anyone handy enough to do car maintenance…

     

    That rules me out.  

    Heikki Lindholm wrote:

     

    …A few years ago, I remember seeing an Australian Apple service tech advertising that they can repair the LCS…

     

    Autralia is a wee bit too far away from my location in Northern California.  Hope someone has a lead closer to me.  

     

    Thanks anyway.  Your posts have been tremendously helpful. 

  • by Chris323i,

    Chris323i Chris323i Feb 13, 2012 3:37 PM in response to Chris323i
    Level 1 (0 points)
    Feb 13, 2012 3:37 PM in response to Chris323i

    The install has worked very well and I am actually posting this from my G5. Installation of the LCS was not an issue at all.

    I have been running the computer since last night and no leaks or stange issues/noises. Fans have been running at a slight to moderate pace during use. What a machine this is! Very fast!

    I give this project about an 7 out of 10 in difficulty but mainly because of the precision work that must be done when reconstructing items. Overall, I spent about $100 in parts. I don't believe anyone will be able to pry this machine away from me in the future.

     

    Here is a shot of iStat I have just taken after running all day and night with a multitude of programs running.

    /___sbsstatic___/migration-images/175/17586484-1.jpg

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