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.

PowerMac

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 BMaverick,Helpful

    BMaverick BMaverick Mar 8, 2012 6:03 PM in response to Fipps
    Level 1 (10 points)
    Mar 8, 2012 6:03 PM in response to Fipps

    The thermal paste used on the LCS blocks is Shin-Etsu MicroSI X23-7762.  The formula works well under higher thermal loads than the AS-C.  The X23 was chosen since it is non-conductive. 

     

    When ordering the X23, make sure the tube is within 6 months of manufacture for the best results.  To store, place in a clean coffee mug in the back of your fridge with the applicator tip facing down.  This will extend the shelf life many more months.

     

    When applying the thermal paste, do a dot-by-dot matrix application on the block surface.  Do not place a glob in the center to smear outward.  A typical pattern would look like this: http://img20.imageshack.us/img20/3466/pastespots.jpg    Each dot must be a miniscual dab.


  • by Heikki Lindholm,

    Heikki Lindholm Heikki Lindholm Mar 8, 2012 10:30 PM in response to Fipps
    Level 1 (135 points)
    Mar 8, 2012 10:30 PM in response to Fipps

    Fipps, I just tore down the system to replace the pump with a Laing DDC-3.2. So, we'll see over the weekend how that goes. The pump's actual full speed depends on the model. If memory serves, it's 3900 for the DDC-3.1 and old DDC-1 pumps and around 4500 for the DDC-2 and DDC-3.2 pumps. Apple's PMU/SMU restricts the speeds between 1200 and 3600.

     

    If you want comparable results and can provide ftp/web space, I can upload my test cd somewhere, it's about 200 MB. I was lazy to prune it. My web provider doesn't give that much space for homepages without extra money. I originally made the CD because I was thinking I'm paranoid and wanted some straight numbers; I had the machine looked at by Apple Service center techs and, after many days of diagnostics, the end result was me giving them money and them claiming all the fan noise was completely normal with "these hot G5s."

     

    As Bmaverick notes, your thermal grease choice wasn't ideal. The newer putty-like greases (resembling the Shinetsu stuff) might work as well - the Shinetsu grease wasn't locally available, so I ordered from the US. Thanks, BMaverick for the application instructions - I used a blop-in-the-middle approach last time, but will try this now.

  • by Fipps,

    Fipps Fipps Mar 9, 2012 12:49 PM in response to Heikki Lindholm
    Level 1 (0 points)
    Mar 9, 2012 12:49 PM in response to Heikki Lindholm

    You both may be right for the thermal grease (also AS Ceramique worked quite well for me up to now and should at least be non-conductive too). Anyway, the Shin-Etsu is available here to an affordable price. So i will give this a try. Very soon, i think. Also the dot matrix application is valuable advice. I used to work from the center too.

     

    But i have my doubts, the thermal grease thing beeing the main reason for the persisting heat problems. I'm afraid, symptoms are more likely pointing in the direction of too little coolant interchange at the cooling point, as temps are ok as soon as the pump spins up. So i will check this again.

     

    As for the Apple "Service" People, they seem to be the same anywhere in the world. If you like to fix instead of buying new, in particular older parts, you're on your own.

     

    Yes, comparable results would be nice. I can provide some space accessible by ftp. Is the mail adress at the end of your work log still active to send you the account data?

  • by Heikki Lindholm,

    Heikki Lindholm Heikki Lindholm Mar 9, 2012 12:55 PM in response to Fipps
    Level 1 (135 points)
    Mar 9, 2012 12:55 PM in response to Fipps

    Yeah, thermal grease isn't probably the main culprit and yes, the e-mail address is still valid.

  • by BMaverick,

    BMaverick BMaverick Mar 9, 2012 5:33 PM in response to Fipps
    Level 1 (10 points)
    Mar 9, 2012 5:33 PM in response to Fipps

    Well, all of the pumps are shown here in the last image:

     

    http://bmaverickddcpumps.wordpress.com/buy-ddc-pumps-here

     

    This should give you a clue.

     

    Lately, the RASA owners are snarfing up the pumps more frequently than any other WCing group.  It seems that the RASA 750 pump is flawed and there is really no good replacement for the loop other than a compact DDC-1T at 10W.  XSPC has sold several hundred of these WCing kits.  The pumps last about 1-1/2 years, just after warranty before dying.

  • by Otis1,

    Otis1 Otis1 May 26, 2012 2:00 PM in response to Heikki Lindholm
    Level 1 (0 points)
    May 26, 2012 2:00 PM in response to Heikki Lindholm

    hey i need some help with mine i have the quad 2.5 8GB of ram cpu b over heats in about 10mins. so someone said rebliead it cuz the water has dryed up cuz there was no leeks so i did. put clean water in got all the air mostly out but one small bubble b 4 the pump tryed runing it to get it to pump it out but its not pumping that good i used a old pc power box and some clips to make it faster but didt even make the bubble move

     

    btw also toke the pump apart looked good.. replaced some hose put some good clear hose on 2 c for air

    idle is now at 59 on cpu a and 85 on cpu but the monet i use it. it over heats

     

    maybe my pumps **** it works but its not pumping good if at all

     

    idk im stomped mabe its an air lock but i put water in the pump i dont really have money for parts the water alone was 6 bucks plez help poor kid in canada this is my frist lcs and its a pain cuz its apple

  • by Heikki Lindholm,Solvedanswer

    Heikki Lindholm Heikki Lindholm Jul 22, 2012 5:01 AM in response to Heikki Lindholm
    Level 1 (135 points)
    Jul 22, 2012 5:01 AM in response to Heikki Lindholm

    I finally got around to doing a small write-up of changing/repairing the pump on the LCS unit. The machine works fine, and I consider the project now finished.

     

    http://www.saunalahti.fi/~holindho/g5-quad-v1-lcs-repair-pump.html

     

    For reference, the initial rebuild:

     

    http://www.saunalahti.fi/~holindho/g5-quad-v1-lcs-repair.html

     

    I also reduced the photo resolution and linked the high res photos instead.

  • by Ramón G Castañeda,

    Ramón G Castañeda Ramón G Castañeda Jul 22, 2012 2:23 PM in response to Heikki Lindholm
    Level 4 (1,468 points)
    Desktops
    Jul 22, 2012 2:23 PM in response to Heikki Lindholm

    Thank you far sharing this, Heikki.  Very impressive documentation.

  • by pocketprobe,

    pocketprobe pocketprobe Sep 17, 2012 1:44 PM in response to Ramón G Castañeda
    Level 1 (0 points)
    Sep 17, 2012 1:44 PM in response to Ramón G Castañeda

    What are the phillips screws on the edges of the water block? I ended up destroying most of my screws removing them,

  • by BMaverick,

    BMaverick BMaverick Sep 17, 2012 6:45 PM in response to pocketprobe
    Level 1 (10 points)
    Sep 17, 2012 6:45 PM in response to pocketprobe

    The screws will always break taking them out, they were installed with Loctite.

     

    If memory servers, those are M3.  Don't recall the thread spacing though. 

     

    http://bmaverickddcpumps.wordpress.com/g5-spare-parts

  • by CGFMaster,

    CGFMaster CGFMaster Oct 21, 2012 10:43 AM in response to Heikki Lindholm
    Level 1 (0 points)
    Oct 21, 2012 10:43 AM in response to Heikki Lindholm

    I've read through the whole post and I want to hook up the Panasonic version up to a GPU.
    First though I want to see if it still works via a PSU.

    But I can't determine what the pinout is for the voltages/tach on the wiring.

     

    There are only 6 connection points at the MB side of the adapter, but midway throught the wires it has a 6 connection adapter in which the outermost pins have 1 wire input (from MB side) and a two wire output to the LCS side). Would that be indicative of a 12v or a GND? Both of the wires are connected to the one wire coming from the MB.

     

    I can get pictures of the pump circuit board if needed. The model number didn't return any search results.

  • by Patrick 01,

    Patrick 01 Patrick 01 Feb 11, 2013 7:22 AM in response to Chris323i
    Level 1 (80 points)
    Feb 11, 2013 7:22 AM in response to Chris323i

    Chris323i wrote:

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

     

     

     

    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.

     

    Chris323i:

    I have the same unit

    Did you keep the flexible pastic hosing or replace it?

    I see the valves where you cut the ports and used a clamp, are they holding up[ as there is no barb ?

  • by romko23,

    romko23 romko23 Feb 11, 2013 12:06 PM in response to Patrick 01
    Level 2 (395 points)
    Feb 11, 2013 12:06 PM in response to Patrick 01

    Sorry to chime in, but is your LCS the dual or single version? The single is by far the more reliable one and it might just be to your advantage to replace the dual with the single pump.. Those came with the later 2006 G5 Quads between April and August of 2006.

  • by Patrick 01,

    Patrick 01 Patrick 01 Feb 11, 2013 12:38 PM in response to romko23
    Level 1 (80 points)
    Feb 11, 2013 12:38 PM in response to romko23

    romko23 wrote:

     

    Sorry to chime in, but is your LCS the dual or single version? The single is by far the more reliable one and it might just be to your advantage to replace the dual with the single pump.. Those came with the later 2006 G5 Quads between April and August of 2006.

     

    I've done a lot of googling and found many statements that the dual version (cooldigy / dephi) is the more more reliable. Some even stating it was the later design. So I can't say for sure. I'm content to stick with my dual as it shows no signs of leakage nor crystalization nor low fluid etc . . I also have a dual panasonic in my 2.7 and that was considered a better design as well by some.

    So who's to say . . .

     

    My  issue is cpu B temps are higher then cpu A cores by 15 on one and 20 the other

    This is only in highest performance with the cpus maxed and stays well below temp

    At reduced performance and max cpus the difference is much less

    At idle and regular use the temps are very close

     

    I'm thinking the cpu B pump might have some build up or is weak etc . .

    May swap cpu positions and see if the temp issue follows the cpu or stays the same

    Id like to flush any debris or build up in the pumps  or replace the pump as needed

    Any thoughts towards this are appreciated

  • by romko23,

    romko23 romko23 Feb 11, 2013 9:32 PM in response to Patrick 01
    Level 2 (395 points)
    Feb 11, 2013 9:32 PM in response to Patrick 01

    Patrick,

     

    I read somewhere, can't remember the website that the single pump came out in April 2006 up until the end of the Quad's run which was August 2006. The dual pump LCS was the first I believe. I will have to research it a bit more.

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