Quad G5 Liquid Cooling Pump Chugging, nasty thermal disparity between cpu's

There is a thermal sensor, it detects voltage and then calculates likely heat! there is a link somewhere in this thread to an IBM document describing this system at chip level.

I had a similar problem, no obvious signs of leaks but dismantling and rebuilding helped. It might help you to remove CPU B completely if it turns out to be a bad thermal sensor.

Andy

Mark,

Most any 12VDC source would work. A battery would be fine.
The arctic silver 5 I put a light coat on the die using a plastic bag and my finger in the bag.

My fans will spin up when load occurs, then back off when it stabilizes. That's normal as far as I know.

I ended up getting a different tray when I ordered the replacement CPUs. The seller had plenty of Powermac G5 parts on hand. Most anyone selling powermac G5 parts, especially CPUs, power supplies, logic boards, usually have the cases and other pieces. Mine started corroding and I replaced it.

Here is info on the absorbent pad #922-6551
http://www.applepalace.com/apple-mac/apple-parts/powermac-g5-parts/power-mac-g5- june-2004/pad-absorbent-power-supply-cover-pkg.-of-2-g5-922-6551.asp

Ok, don't need a closeup of the pump connection. You have two pins that are close together, then the other two have empty connections between each other. With the locking tab of the connector facing toward the center of the earth, you should see pin 1 2 4 and 6 from left to right. 12V goes to the left one and the one above the tab which is pin 4, and ground goes to the very right one which is pin 6. Pin 2 needs no connection. Pin 2 is immediately right of pin 1.

1 2 - 4 - 6

12V 1 & 4
Common Ground to 6

Pin 2 is tachometer output.

This is the information I took from Paco Meader's post in this thread on May 8 2009.

Pinouts be different on the newer cooling systems with dual pumps.

-William

Message was edited by: Berzerkula

Hello. My Core B is MUCH hotter than core A, perhaps 50+ degrees hotter. Today my Quad Core did a thermal shutdown. Ouch. I looked inside, all seems well, though obviously all is not well.
I am seeking PictoriaI nstructions on removing the Cooling Unit, a list of tools needed, and parts, thermal grease, coolant, etc. Also, if Processor B is bad, can I replace it? If so, where can I purchase one?

Thanks,
Doctor Ken
10/1/09

Hello:
How do I remove the cooling unit and processor?
Thanks,
Doctor Ken

Good idea to get a copy of the service manual, it gives all this information and loads more that is worth knowing if you are going to try and dismantle the quad.

As far as getting spare processors, I have had no luck sourcing any. It seems they have to be linked to the motherboard in some way, i.e. some don't work with different boards and I have no information on which ones or why.

You can completely remove the processor if there is no way to correct it though. Have you read right through the thread there are some pics etc.

I hope it's OK to just jump in here...

I had need to rebuild the LCS on my dual 2.5 G5 3 or 4 months ago. Cleaned, sealed, new pump and tubing. Everything went well.
Now there's a little air in the system - no leaks - just a little air pocket after settling out and running for 3 months. Enough that you hear a little fizzy sound out of the pump here and there. I know that Apple gets ALL the air out by drawing vacuum 1st. I put a foot of tubing on the fill valve as a reservoir tank and ran it till it was almost free of air. I thought there might be some pockets in the radiator that would need a lot more time to settle out and sure enough.
Anyway, having to disassemble this periodically to top off would be crummy. I do need to address this before it starts beating on the pump. I'm thinking of maybe installing a t-fitting with an extra length of tubing with a plug in the end. The top of the tube could sit atop the radiator, making it the highest point in the system. Then any small air bubbles would rise to the top of this make-shift reservoir. Anyone have an opinion on that?

Jim,

That's overkill. What you should do is follow my posts on what I did. Have a reservoir and extra tubing available and run the system while filling it. You will get the air bubbles out that way. Use buoyancy and tape to edge the fluid at the tip of the tubes, seal then remove the extra tubing and seal quickly. Having the radiator at the bottom and the pump inlet at the top will minimize bubbles in the system. I haven't had an issue with bubbles at all. Fill the system, run the pump and prime it if needed, let it run a bit, stop the pump, lift the reservoir till the tube ends are full, tape it closed, remove the reservoir and the hose and seal with a thumb, and close the system.

Practice on a lab system if required. Those with the dual pump system have less room to work with, so my method is torture.

-William

FWIW, Mike at "XLR8YourMac" was kind enough to post my LCS overhaul pics at his site:

http://www.xlr8yourmac.com/systems/G5CoolantLeak_Repair/G5_CoolantLeakRepair.html#storytop

Berzerkula(William),

Using Network Utility\info, I find the default for Network interface set to fw2. I changed the NI to en0 and it reverts back to fw2. Any ideas how to reset it to en0? Or do need a card (and the onboard ethernet is bad)?
thx
Mark