Quad G5 CPU Cooling

[AppleGeek1127]

I have a G5 quad that posts, chimes and starts booting. However, the CPU temperature increases to roughly 80 degrees, the fans spin at maximum RPM and the system promptly shuts down. I cannot complete a thermal calibration with ASD. As a result, I’m certain the issue is hardware related.

There does not appear to be any leaks or corrosion from the liquid cooling system. Despite not being super familiar with the G5’s internals, I’m aware this is a common issue.

There there are 2 red LEDs (over temp and check stop) when the system is powered on. I have tried different RAM modules, so I do not believe they are an issue.

As seen in the photos, the anti static pad had completely disintegrated, so I scraped away it off and some adhesive along with it.

What is the best course of action for this machine to maximize its lifespan? Would it be better to repair it with its current hardware or replace the cooler with something else? I want to make sure I know what I am doing before tearing any further into it.

 

[MoerBoer]

Have you tried re-applying new thermal paste to the CPU’s?

 

[AppleGeek1127]

Have you tried re-applying new thermal paste to the CPU’s?

I have not repasted or reseated the CPUs. I wanted to figure out whether I was going to keep using the original LCS first.

 

[mustagcoupe]

The liquid cooling system likely needs to be flushed clean and refilled. There are guides on this site on how to do that. The thermal paste on both the processors and the u3 chip on back of the board will need to be replaced no matter what. To do this you need to disassemble basically the entire system. Be careful with the processor support bar, make sure it does not get caught on anything and fall on the board....

 

[AppleGeek1127]

The liquid cooling system likely needs to be flushed clean and refilled. There are guides on this site on how to do that. The thermal paste on both the processors and the u3 chip on back of the board will need to be replaced no matter what. To do this you need to disassemble basically the entire system. Be careful with the processor support bar, make sure it does not get caught on anything and fall on the board....

I will attempt this, and post an update when I’m done! I appreciate the heads up.

 

[dpfenninger]

I have a Quad G5 that I received recently that's exhibiting basically the same thing...powers on, boot chime, and then the same two red LEDs on the motherboard and the system freezes. I've got the LCS and CPU chassis opened up and fans removed, but don't have the long enough hex drivers to remove it from the system yet. But I'm curious to know if you were successful in removing, applying new thermal paste, reseating, etc. I really hope I don't have to rebuild or refill the LCS as that is WAY above my skillset...hopefully just cleaning out the existing system will revive it.

 

[dpfenninger]

Finally got the long-enough hex wrenches to remove the CPU/LCS unit. Took it out, sprayed a LOT of dust out of it and the fans, put it back in, and same thing... got an initial boot into OS X, but after rebooting, nothing but loud fans, a black screen, and the same two red LEDs on the motherboard. Still can't pull up the early boot or OF screens, too.

Next step is one that I was hoping I wouldn't have to do as it looks like it's additional surgery on the CPU unit: new thermal paste on the CPU dies. But I haven't been able to find a really good, clear tutorial for the Quad specifically. Can anyone point me the right direction for how to do this with a Quad G5?

Otherwise, any other ideas for what might be causing this issue? Have looked around online for a CPU/LCS replacement unit, but they're all heinously expensive so would rather try to resuscitate this before going that route.