Quad G5 Fan Issue

[AppleGeek1127]

I just purchased a Quad G5 locally for a very good price... I brought the thing home, fired it up and the fans seem to be spinning at 100% constantly.

I dusted the thing out and it’s still doing this. I’m afraid to run the machine as something is very clearly not right. Obviously I don’t want to kill a Quad G5.

Does have any suggestions or know why this might be happening? Thanks.

 

[eyoungren]

Your next steps would be checking the condition of the thermal paste and how well the LCS is functioning.

 

[B S Magnet]

Your next steps would be checking the condition of the thermal paste and how well the LCS is functioning.

Correct.

In addition, because the thermal paste will all but likely need to be replaced (since checking it will also necessitate a clean-and-replace), the first thing you will want to do immediately after cleaning and re-pasting with new thermal paste is to boot from the ASD 2.6.3 — Apple Service Diagnostic — disc (which is available online and can be burnt to DVD beforehand) and run thermal calibration.

While you’re re-pasting, you’ll also have the opportunity to visually inspect the inside-bottom of the case on and around the power supply unit for signs of liquid corrosion.

 

[AppleGeek1127]

Correct.

In addition, because the thermal paste will all but likely need to be replaced (since checking it will also necessitate a clean-and-replace), the first thing you will want to do immediately after cleaning and re-pasting with new thermal paste is to boot from the ASD 2.6.3 — Apple Service Diagnostic — disc (which is available online and can be burnt to DVD beforehand) and run thermal calibration.

While you’re re-pasting, you’ll also have the opportunity to visually inspect the inside-bottom of the case on and around the power supply unit for signs of liquid corrosion.

No signs of liquid corrosion. Replaced the thermal paste and it’s still the same.

 

[AppleGeek1127]

Your next steps would be checking the condition of the thermal paste and how well the LCS is functioning.

Replaced the thermal paste. No signs of liquid corrosion. No dice. How would I know if the LCS is functioning?

 

[DeltaMac]

Did you run the calibration routine on the ASD dvd?

Is the clear plastic air deflector in place?

 

[AppleGeek1127]

Did you run the calibration routine on the ASD dvd?

Is the clear plastic air deflector in place?

I’m going to run the thermal calibration now. I think that may solve it because I was able to use Floodgap’s QuickFans and the temperatures were only in the 40s.

 

[AppleGeek1127]

Did you run the calibration routine on the ASD dvd?

Is the clear plastic air deflector in place?

I didn’t see the other part of your response initially. Yes, the plastic air deflector is not n place. I tried running calibration, but after several hours it’s still stuck here.

 

[DeltaMac]

That is easy to explain...
Calibration or not, the fans will run full speed if the air deflector is not installed, or not seated in place properly.
And, the calibration procedure will not finish unless that air deflector is installed.
(I'm guessing that you have not worked on a PowerMac G5 before. )

 

[AppleGeek1127]

That is easy to explain...
Calibration or not, the fans will run full speed if the air deflector is not installed, or not seated in place properly.
And, the calibration procedure will not finish unless that air deflector is installed.
(I'm guessing that you have not worked on a PowerMac G5 before. )

Is that installed properly or not? No I haven’t worked on a G5 before, hence the reason I made this thread asking for help...

 

[B S Magnet]

Is that installed properly or not? No I haven’t worked on a G5 before, hence the reason I made this thread asking for help...

View attachment 974034

Yes, that is correct. Now give thermal calibration a re-try.

 

[eyoungren]

Is that installed properly or not? No I haven’t worked on a G5 before, hence the reason I made this thread asking for help...

View attachment 974034

The reason this plastic shield is important to the normal operation of the G5 is because of the heat that G5s produce. The chips run hot and it's for this reason that there was never a G5 laptop (although Apple did look into it).

So in order to make everything work and keep the chips cool the design of the G5 was very specific. Apple even used that fact (and diagrams) in its promotion of the G5. There are thermal zones, one for the PSU, one for the CPU, one for the peripherals and one for the drives. The way the plastic shield is molded, it's designed to be an integral part of making those thermal zones function properly. There is even a sensor that detects when the shield is missing.

So, without the shield, it doesn't work right and the fans ramp up to full speed as the only way to compensate for the amount of heat the CPU(s) produce.

 

[DeltaMac]

If the fans STILL are up, even with the deflector in place, check the bottom (right, I think) tab on that deflector, where it goes into the chassis. It MUST have an opaque covering on that tab, as it has to block a light sensor underneath the chassis, where the tab is located. It's usually a length of silver/aluminum tape.

 

[AppleGeek1127]

Yes, that is correct. Now give thermal calibration a re-try.

That is the way it was installed when I performed the calibration. I didn’t touch it, I just took the side panel off to take a picture. Is there any other reason why the calibration could be failing?

 

[AppleGeek1127]

The reason this plastic shield is important to the normal operation of the G5 is because of the heat that G5s produce. The chips run hot and it's for this reason that there was never a G5 laptop (although Apple did look into it).

So in order to make everything work and keep the chips cool the design of the G5 was very specific. Apple even used that fact (and diagrams) in its promotion of the G5. There are thermal zones, one for the PSU, one for the CPU, one for the peripherals and one for the drives. The way the plastic shield is molded, it's designed to be an integral part of making those thermal zones function properly. There is even a sensor that detects when the shield is missing.

So, without the shield, it doesn't work right and the fans ramp up to full speed as the only way to compensate for the amount of heat the CPU(s) produce.

View attachment 974040

Hmm, very interesting. I remember them talking about trying to shove a G5 into a PowerBook. Wish that could have happened, but given that information it seems unrealistic.

 

[eyoungren]

Hmm, very interesting. I remember them talking about trying to shove a G5 into a PowerBook. Wish that could have happened, but given that information it seems unrealistic.

Yeah, the thermal issues, combined with the inability of the manufacturer to supply demand as well as the desired specifications are the major reasons Apple switched to Intel CPUs.

 

[AppleGeek1127]

Yeah, the thermal issues, combined with the inability of the manufacturer to supply demand as well as the desired specifications are the major reasons Apple switched to Intel CPUs.

Very sad. PowerPC machines have so much character. Plus Apple’s switch to Intel essentially made the desktop CPU market a duopoly. At least I still have a few of them around. I hear you have one or two yourself

 

[AppleGeek1127]

If the fans STILL are up, even with the deflector in place, check the bottom (right, I think) tab on that deflector, where it goes into the chassis. It MUST have an opaque covering on that tab, as it has to block a light sensor underneath the chassis, where the tab is located. It's usually a length of silver/aluminum tape.

It is on there, if this is what you’re referring to.

 

[RumorConsumer]

It is on there, if this is what you’re referring to.View attachment 974325

Yep thats it. Fans on that guy are not quiet. I had one when they first came out. Had the 7800GT and twin 74gb Raptors RAID'd. When the power supply died I was in the shower in the next room and it sounded like a shotgun had been fired in my apartment it was so loud. I was a genius at the time at Apple and my boss let me replace my own power supply which is usually quite frowned upon to work on your own hardware. I think it was bc he would have had to do it and he didn't like working on towers. I lived for it.

 

[B S Magnet]

Yep thats it. Fans on that guy are not quiet. I had one when they first came out. Had the 7800GT and twin 74gb Raptors RAID'd. When the power supply died I was in the shower in the next room and it sounded like a shotgun had been fired in my apartment it was so loud. I was a genius at the time at Apple and my boss let me replace my own power supply which is usually quite frowned upon to work on your own hardware. I think it was bc he would have had to do it and he didn't like working on towers. I lived for it.

Yikes.

I dread the possibility/day of my PSU dying on my DP2.0 — not least of which the possibility of a loud bang, but also the sheer challenge in finding a working replacement at this point. Its main power demand, after the CPUs, is the Cinema Display (20") and the running of six internal drives — five of them 3.5" HDDs.

As for the OP, I would be intrigued to see in iStat Menus what all the fan sensors are reading whilst the Quad is idling. for folks with Quad G4s, these data would be helpful to take into account.

 

[Nikolaosth]

The thermal calibration fails with the system freezing while calibrating because the cooling system is failing . It will either say that the calibration failed or it will freeze . I've seen this happen .

 

[NikolaPPC]

The thermal calibration fails with the system freezing while calibrating because the cooling system is failing . It will either say that the calibration failed or it will freeze . I've seen this happen .

Yep, my Quad has a failing LCS and the thermal calibration also gets stuck at the same point.


Cheers, Nikola!

 

[AppleGeek1127]

Yep, my Quad has a failing LCS and the thermal calibration also gets stuck at the same point.


Cheers, Nikola!

So would you recommend replacing the LCS?

 

[NikolaPPC]

So would you recommend replacing the LCS?

Absolutely not!
The replacement LCS also has over 15+ years, it will fail at some point.
It is not the most convenient thing to do, but disassembling the LCS, cleaning & flushing the pump and the radiator, changing the coolant & hoses can provide the life of another 10+ years.

I have saved the web page of some guy cleaning and repairing his Quad and have attached those files (one is for the whole LCS system, the second is for the pump).


Cheers, Nikola!

 

[AppleGeek1127]

Absolutely not!
The replacement LCS also has over 15+ years, it will fail at some point.
It is not the most convenient thing to do, but disassembling the LCS, cleaning & flushing the pump and the radiator, changing the coolant & hoses can provide the life of another 10+ years.

I have saved the web page of some guy cleaning and repairing his Quad and have attached those files (one is for the whole LCS system, the second is for the pump).


Cheers, Nikola!

Looks like I have my work cut out for me. Thanks so much for your help!