Help: Power Mac G5 - Fan issue.

[Mark Lang]

Wondering if anyone is able to help, got a bit of a mystery on my hands here.

A friend of mine gave me two Powermac G5s recently a 7,2 and 7,3. The 7,2 works fine no issues there, however the 7,3 is a different story.

The 7,3 seems to exhibit high fan usage all the time when it's on. I know this could be caused by the plastic inserts little reflective thingy. But I'm sure it's not that as I've tried the plastic insert, out the 7,2 and it doesn't work either.

I've also attempted terminal calibration with the AHT disc to no joy. As this just complains about a fan speed error, again like the ambient light sensor isn't working. Also tried the NVRam and PR resetting both. Also changed the battery as well to no avail stumped.

Wondering if there is some other way to control the fans through open firmware or something.

Anyone have any ideas? I'd be enterally grateful, the machine is fine literally apart from this. No other issues which is a shame.

 

[AphoticD]

It could be the door sensor at fault as you're saying. It's also possible the CPU needs a fresh application of thermal paste. I would recommend installing iStat Pro widget, iStat menus or Temperature Monitor to see a full reading of temperatures and fan speeds. This should show which fan(s) are ramping up and which temps are over.

 

[Mark Lang]

Thanks AphoticD. I'll try the widget tonight. If it is the door sensor, is there any workaround for that or would you have to replace sensor?

It could be the door sensor at fault as you're saying. It's also possible the CPU needs a fresh application of thermal paste. I would recommend installing iStat Pro widget, iStat menus or Temperature Monitor to see a full reading of temperatures and fan speeds. This should show which fan(s) are ramping up and which temps are over.

 

[AphoticD]

Thanks AphoticD. I'll try the widget tonight. If it is the door sensor, is there any workaround for that or would you have to replace sensor?

I imagine you could just short the circuit to bypass the sensor - Find the door sensor’s connection on the logic board and jump the pins to see if it behaves differently.

I’ve done this technique with the thermal HDD sensors in many intel iMacs, (including my personal 2009 21.5”), which go full throttle on the fan speed when you replace the stock HDD with an aftermarket HDD or SSD.

Obviously a word of warning though that you risk doing irreparable damage if you short something that causes another component to fry. Proceed with caution

 

[Mark Lang]

Thanks that makes sense. Would you know where abouts the door sensor is on the Power Mac 7,3. Appreciate your help thus far.

I'm thinking as well that it's maybe not the CPUs overheating as I believe this model has water cooling though not sure.

I imagine you could just short the circuit to bypass the sensor - Find the door sensor’s connection on the logic board and jump the pins to see if it behaves differently.

I’ve done this technique with the thermal HDD sensors in many intel iMacs, (including my personal 2009 21.5”), which go full throttle on the fan speed when you replace the stock HDD with an aftermarket HDD or SSD.

Obviously a word of warning though that you risk doing irreparable damage if you short something that causes another component to fry. Proceed with caution

 

[rampancy]

Have you tried looking in the Apple Service Manuals? I don't know off the top of my head if the 7,3 is the original/Early 2005 model, or the Late 2005 model. (Warning, those links go to large PDF files.)

 

[NikolaPPC]

I'm thinking as well that it's maybe not the CPUs overheating as I believe this model has water cooling though not sure.

LCS on these models can have a leakage or the pump can be clogged.
My advice is to remove the processor cover and take a picture for starters.

Cheers, Nikola!

 

[Mark Lang]

Cheers Rampancy the service manuals are really detailed which is great. Had a look and appears the air deflector sensor would require a full tear down to access, which seems quite the task. It could be the cable is just loose for it or the board is dead.

Have you tried looking in the Apple Service Manuals? I don't know off the top of my head if the 7,3 is the original/Early 2005 model, or the Late 2005 model. (Warning, those links go to large PDF files.)

No worries NikolaPPC thanks. Please see CPUs beneath cover, looks fairly clean. But not
sure how they should look if I'm honest. What do you think?

LCS on these models can have a leakage or the pump can be clogged.
My advice is to remove the processor cover and take a picture for starters.

Cheers, Nikola!

I've also noticed oddly the red led for the sensor doesn't show as well if the plastic insert is in or out, unlike the 7,2 food for thought.

Cheers again for the pointers guys.

 

[NikolaPPC]

No worries NikolaPPC thanks. Please see CPUs beneath cover, looks fairly clean. But not
sure how they should look if I'm honest. What do you think?

The only real way to see if the O rings have started leaking (problematic for these models) is to remove the LCS, remove the CPU fron the LCS and inspect around the CPU die. If there isn't oxidation on the capacitors around the die from the leaked liquid, just replace the thermal paste and see if there are better results!

But, before you dive into all that, please install istat menus and report the processor temperature when idle and when you load it.
Also, check energy saver in the settings to see if the processor performance is on highest, automatic or reduced mode!

I can't help you much with the door sensor, maybe other more experienced members can give you a proper guide how to do it.


Cheers, Nikola!

 

[Mark Lang]

The only real way to see if the O rings have started leaking (problematic for these models) is to remove the LCS, remove the CPU fron the LCS and inspect around the CPU die. If there isn't oxidation on the capacitors around the die from the leaked liquid, just replace the thermal paste and see if there are better results!

But, before you dive into all that, please install istat menus and report the processor temperature when idle and when you load it.
Also, check energy saver in the settings to see if the processor performance is on highest, automatic or reduced mode!

I can't help you much with the door sensor, maybe other more experienced members can give you a proper guide how to do it.


Cheers, Nikola!

No worries Nikola.

Sorry for delay in getting to you, had to install leopard again onto the 7,3. Hopefully this what your after.

 

[NikolaPPC]

Are those idle temps or under load?


Cheers, Nikola!

 

[Mark Lang]

Are those idle temps or under load?


Cheers, Nikola!

Hi Nikola,

Took this screenshot with the safari web browser open in background so under load? But nothing really happening in browser. Can take another if you want without the browser open. Did notice they dropped to about 57-49ish as it went on for CPU temps. Cheers.

 

[NikolaPPC]

Open TFF and open some youtube video in it, and take a full picture of the istat menu, so the cpu load is visible.

Also, did you check on what the processor performance is set under energy saver in options?

If the temperatures get too high (75-80°C or more) when under load, new thermal paste has to be changed first.
When you remove the processor from the LCS, you can inspect if there's corrosion around the caps from a leakage.
If everything is all right, but the fan speed is still too high, there are only 2 possibilities, defective door sensor or LCS failure.
If that's the case you need to open it, flush it, change tubes etc..
All about disassembly & repair can be found in the link below, where the exact model like yours (DP 2.7Ghz) has been repaired.

-link-

Cheers, Nikola!