Sidebar Sidebar
Become a MacRumors Supporter for $50/year with no ads, ability to filter front page stories, and private forums.

G5 starts with loud fan noise?

Patth9

Patth9

macrumors regular
Original poster
Jun 28, 2007
217
37
I have a Power G5 Mac, and I'm using Tiger. Can anyone tell me why, when I first start the Mac up, the fan comes on loudly and stays on, sometimes reeving a few times, but returns to the loud noise untill I shut down? I can maneuver a little, but it's scary!

I should add that there have been many times when the Mac would start quietly, and without notice the fans would turn on and stay on. I'm not 100% sure it is the fan, but I can't imagine what else it would be.

If anyone has an answer or needs more information from, I'd sure be obliged if you would share your knowledge with me.

Patt

Using 10.4.11
Processor Dual 2 GHz PowerPC G5
1 GB DDR SDRAM,
POWER MAC7,3
 
Last edited:
I may remember wrong but there should be red led lit if overheating condition is reached. You could try removing the aluminium door (but not the plastic cover) and using the machine. Also if the plastic cover is not securely in place it might trigger fans.
 
Possibly a bad temperature sensor. Also, the fans always run at full speed when the plastic inside cover is not in place.
 
I have the same machine and recently had the same problem, or a similar one.

I unplugged it for a day or so, took out the little half battery, reset the PMU by pressing the little button down on the lower edge of the logic board (NB Be careful here with this, read info on the net how to do it ), then put in a new battery.
Started her up and my racing fans were gone, or it's been good for the last few days.

Have read you can do the PMU reset with the battery in, but I wanted to make sure I had a good battery in there so that is why I did it this way.
Battery looked like it was an original from 2003, and in the end it was, when I took it out I looked at the date.

I've got 8GB's of ram in this, so next thing I was going to do was do some testing on taking out ram etc.
Thought the battery though was a good place to start troubleshooting the noisy fans, and in my case it seems to have solving the issue I had.
 
Overheating?

Download "Hardware Monitor Lite" It's a free program and will tell you if you have a cpu overheating issue. If one or both CPU's are overheating (+65 degrees C) the fans will run continuously. I just fixed this issue.
 
The fans will go into overdrive if the reflective surface over the light sensor (on the back tab of the clear, plastic, airflow cover) is scratched or defective.

Try this:

1. Open the G5
2. Remove the clear, plastic air panel.
3. Take a strip of paper, 1 1/4" wide, and gently slide it into the slot normally occupied by the rear tab of the airflow cover.
4. Now, reset the PMU, if desired.
5. Power the machine on, without closing it first.
6. Report if the problem has ceased.

Check the tab on that clear panel to see if the reflective tape has degraded, or fallen off. It should refract light, like a translucent hologram film.

If this doesn't help, the light sensor itself may be dirty, and needs to be cleaned.
 
AmestrisXServe said:
The fans will go into overdrive if the reflective surface over the light sensor (on the back tab of the clear, plastic, airflow cover) is scratched or defective.

Try this:

1. Open the G5
2. Remove the clear, plastic air panel.
3. Take a strip of paper, 1 1/4" wide, and gently slide it into the slot normally occupied by the rear tab of the airflow cover.
4. Now, reset the PMU, if desired.
5. Power the machine on, without closing it first.
6. Report if the problem has ceased.

Check the tab on that clear panel to see if the reflective tape has degraded, or fallen off. It should refract light, like a translucent hologram film.

If this doesn't help, the light sensor itself may be dirty, and needs to be cleaned.
Click to expand...

AmestrisXServ, it's been a while since I was able to get back to the noise fan problem. I want to follow your instructions, but I'm a bit muddled.
You instruct:

3. Take a strip of paper, 1 1/4" wide, and gently slide it into the slot normally occupied by the rear tab of the airflow cover.

4. Now, reset the PMU, if desired.

Well, I don't know how to follow your #3 step. I have the outer cover off and the clear plastic panel is removed. Where is the "rear tab of the airflow cover?

AND:
CAN NOT FIGURE OUT WHERE THE TAB IS ON THE CLEAR PANEL in you rest of your instuctions.

"Check the tab on that clear panel to see if the reflective tape has degraded, or fallen off. It should refract light, like a translucent hologram film."

I looked up PMU and will deal with that after I find where to put the 1 ¼ piece of paper.


I did unplug the hard drive fan, which really lowered the noise, but I don't think this is wise to run the Mac without this particular fan running.

Please set me straight, if you please.

Patt
 
Patth9 said:
AmestrisXServ, it's been a while since I was able to get back to the noise fan problem. I want to follow your instructions, but I'm a bit muddled.
You instruct:

3. Take a strip of paper, 1 1/4" wide, and gently slide it into the slot normally occupied by the rear tab of the airflow cover.

4. Now, reset the PMU, if desired.

Well, I don't know how to follow your #3 step. I have the outer cover off and the clear plastic panel is removed. Where is the "rear tab of the airflow cover?

AND:
CAN NOT FIGURE OUT WHERE THE TAB IS ON THE CLEAR PANEL in you rest of your instuctions.

"Check the tab on that clear panel to see if the reflective tape has degraded, or fallen off. It should refract light, like a translucent hologram film."

I looked up PMU and will deal with that after I find where to put the 1 ¼ piece of paper.


I did unplug the hard drive fan, which really lowered the noise, but I don't think this is wise to run the Mac without this particular fan running.

Please set me straight, if you please.

Patt
Click to expand...

You should never run a G5 or any computer with one of its fans unplugged. By the tab he means on the clear shroud you remove.

At the bottom you will see two notches in the plastic sticking out. On the one which is closer to the rear of the G5 apply his steps.
 
Altemose said:
You should never run a G5 or any computer with one of its fans unplugged. By the tab he means on the clear shroud you remove.

At the bottom you will see two notches in the plastic sticking out. On the one which is closer to the rear of the G5 apply his steps.
Click to expand...

Well, my o my, that was certainly a well hidden feature. Thanks, found with it no problem, but the tab cover is securely attached and no scratches. Would you suggest I use a Q-tip or possibly a can of air to clear away any dust down in the , which the inside of the computer certainly has a LOT of, dust that is.

Thanks for the reminder about not running the CPU without a fan. I await the proper cleaning method...before trying other suggestions.

Patt

Patt
 
You may want to run Apple's processor calibration.

That's on the ASD (Apple Service Diagnostic) v.2.5.8 for the PowerMac G5.

You'll need to find someplace to download that.
 
Patth9 said:
Well, my o my, that was certainly a well hidden feature. Thanks, found with it no problem, but the tab cover is securely attached and no scratches. Would you suggest I use a Q-tip or possibly a can of air to clear away any dust down in the , which the inside of the computer certainly has a LOT of, dust that is.

Thanks for the reminder about not running the CPU without a fan. I await the proper cleaning method...before trying other suggestions.

Patt

Patt
Click to expand...

I would use some compressed air on it then. Ensure you hold it a safe distance away and don't tilt the can. If you put it too close and on an angle it will spray liquid out :mad: . You may need to calibrate the CPUs as mentioned by DeltaMac. Jbarley posted a link for the file you need to do so. When you power it on, look through the front of the case by the USB ports. You should be able to see inside and see if a red light is on. It will be rather obvious.
 
Patth9 said:
Well, my o my, that was certainly a well hidden feature. Thanks, found with it no problem, but the tab cover is securely attached and no scratches. Would you suggest I use a Q-tip or possibly a can of air to clear away any dust down in the , which the inside of the computer certainly has a LOT of, dust that is.

Thanks for the reminder about not running the CPU without a fan. I await the proper cleaning method...before trying other suggestions.

Patt

Patt
Click to expand...

Now that you have located that tab, take a strip of white paper, tear off a 1" strip, and fold it, then slide it into the slot where that plastic tab normally fits.

This is to diffuse the light of the sensor, and may help diagnose if the tab on the air shield is faulty.

I have had the actual sensor fail on systems in the past as well, but you want to test it first, as it is a very big undertaking to replace the sensor module.

Resetting the PMU is usually easy on a G5, unless you have a late-2005 model. Unplug the system from power, wait 30-seconds, and reattach it to power. You must remove the power plug from the system, not merely shut the power off.

I have a Dual 2GHz system here at present with a dead sensor board, that does essentially the same thing. I tested the sensor with the piece of paper, and it may shock you that this is the stated procedure in the Apple Service Source manual.

If the paper trick doesn't work, you may have a bad sensor, or your fan load balance may be wrong, in which case, you will need to run the Apple Service Source calibration process as mentioned above.

It is usually wise to run a calibration, prior to dismantling the system to change the sensor module, as you need to strip away many components to change it out.

If you have an air compressor tank, use that, with a tapered nozzle, to clean out the system.
 
AmestrisXServe said:
Now that you have located that tab, take a strip of white paper, tear off a 1" strip, and fold it, then slide it into the slot where that plastic tab normally fits.

This is to diffuse the light of the sensor, and may help diagnose if the tab on the air shield is faulty.

I have had the actual sensor fail on systems in the past as well, but you want to test it first, as it is a very big undertaking to replace the sensor module.

Resetting the PMU is usually easy on a G5, unless you have a late-2005 model. Unplug the system from power, wait 30-seconds, and reattach it to power. You must remove the power plug from the system, not merely shut the power off.

I have a Dual 2GHz system here at present with a dead sensor board, that does essentially the same thing. I tested the sensor with the piece of paper, and it may shock you that this is the stated procedure in the Apple Service Source manual.

If the paper trick doesn't work, you may have a bad sensor, or your fan load balance may be wrong, in which case, you will need to run the Apple Service Source calibration process as mentioned above.

It is usually wise to run a calibration, prior to dismantling the system to change the sensor module, as you need to strip away many components to change it out.

If you have an air compressor tank, use that, with a tapered nozzle, to clean out the system.
Click to expand...

I am a very happy camper, very happy. I used the air can and blew the daylights out of the really dusty innards. I have run the Mac for two days, less the night, and it purrs softer than a kitten. I backed up my second hard drive, which is also on the Mac until I find a replacement for my exterior holder, and the fans only kicked in with noise for a few moments. I didn't try the paper trick as it worked right off the bat.

I will keep this link, from which I have received so many have suggestions, in case I need to start following some of the additional steps down the road.

I am most grateful for all the help. I still want to use my G5 because it contains programs that I still use. I was afraid it was a goner, and now the G5 is the MOST quite it has ever been.

Thank YOU'LL,
Patt
 
You must log in or register to reply here.
Register on MacRumors! This sidebar will go away, and you'll see fewer ads.
Top Bottom
Back