Power Mac G5 Dual Core gets hot and fans run slow

Question

Power Mac G5 Dual Core gets hot and fans run slow

Hello

I have a Power Mac G5 (Late 2005) Dual Core that has fan problems. The temperatures get high and the fans barely spin up. The CPU fans sit at 499 and 515 rpm and when playing Minecraft they go to about 600 rpm and the CPU gets up to 151F. I have ran Apple Hardware Test and it still doesn't work. It is running Mac OS 10.5 and has 6 GB of RAM and has a 500GB hard drive. I have:

Reset PRAM
Re-installed Mac OS X
Replaced Hard Drive
Cleaned dust
Ran AHT
And reset the SMU
Tried editing AppleFan.kext

iStat pro says the fans spin about:

CPU A intake: 499 rpm

CPU A exhaust: 515 rpm

CPU B intake: 499 rpm

CPU B exhaust: 515 rpm

Backside: 1000 rpm

Slots: 1500 rpm

drive bay: 1000 rpm

Is this normal? Do they always spin slow or is there any other things I can do or software to download?

PowerMac, Mac OS X (10.5)

Posted on Feb 15, 2016 4:00 PM

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Answer 1

Feb 16, 2016 4:37 PM in response to Drew Reece

Hi

I turned the computer on and opened the cover and with a flashlight, the red LED is the CHECKSTOP led.

According to the PowerMac G5 late 2005 manual, it says:

No.7 Checkstop red Expected Condition: Off (LED flashes once at startup and then goes off) LED on indicates: CPU hang. Things to check: Check RAM. Is processor assembly seated correctly? Check that mounting screws are properly tightened. Next steps: remove processor assembly and check for damaged pins on connector or logic board connector. Replace processor, if necessary. Replace logic board if necessary.

I ran ASD a last year, but that was with the old MacOSX installation, and the old hard drive. The fans get really loud when running the tests, and it has 6GB of RAM, so the memory tests take really long. Should I run it again?

I've cleaned it out, but I didn't get to the Power Supply or behind the logic board, I have only gotten to the CPU heatsink; and the computer was not very dusty when I got it last year.

The fans spin up a tiny little bit when the cover is removed. When it is off, but plugged in and the cover is removed; the yellow NO_GOOD_TRICKLE LED goes on.

According to my trusty iPad with the service source on it it says:

LED On: AC power OK. Things to check: Check for AC power at the wall outlet, try another outlet. Next steps: Check operation of the air deflector sensor. Replace PSU.

I couldn't remove the CPU heatsink when I was cleaning it yesterday because I don't have a long Hex driver needed to remove the hex screws in the heatsink (there's holes that go down in the heatsink that are long)

The date and time doesn't reset when it is unplugged, so the PRAM battery works. So should I replace the PRAM battery? I have some coin cells somewhere.

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Answer 2

Feb 16, 2016 1:20 PM in response to Community User

Hi

I replaced the hard drive because the other one was failing, but after when I installed Leopard, I restored my documents, apps, etc. from a Time Machine backup. I will make sure next time I use my G5 to start up from the Mac OS X installation disk and do a fresh install (Erase and Install) and then copy only apps that I use often (MS office 2008, etc.) and see if that works.

Thanks for your suggestion. I will try it out right now!

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Answer 3

Feb 16, 2016 1:09 PM in response to BDAqua

The Power Mac G5 is not liquid cooled, so it's not leaking. Thank you though.

It's a 2.3 GHz

I found ASD 2.6.3 on the internet somewhere and I have tried that. Any other suggestions?

My fans spin much slower (as mentioned earlier) and the temperatures get hot when playing Minecraft, etc.

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Answer 4

Feb 16, 2016 2:54 PM in response to Community User

I finished installing Leopard, and installed iStat Menus to see the fan speeds.

It said that the backside temperature sensor is 2012 degrees Fahrenheit, but that can't be true

Whenever I turn on the tower, a little red light comes on when it starts up for a few seconds.

Other PowerMacs sometimes have loud fan speeds or the fans spin up and down based on temperature and CPU usage.

Mine justs sits there at 499 and 515 rpm, put when playing minecraft, they go up to 699 rpm, but BDAqua's temperature readings show much faster speeds.

Is my PowerMac's fans normal or do I need to do anything else. I have only installed iStat Menus, nothing else.

How do I get my fans to spin like BDAqua's when my CPU is at 151ºF but BDAqua's CPU is at 127ºF and spinning way faster than mine at 151?

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Answer 5

Feb 16, 2016 5:52 PM in response to Drew Reece

Hi

I replaced the PRAM battery, reset the PRAM, and reset the SMU, but I still get the checkstop LED; but when I open the air deflector sheild; the fans actually spin slower than 499 and 515 rpm, and the CPUs get hotter. For example, if CPU A is at 90ºF then it will go up to ~110º and stay around that.

I got the PowerMac at the MIT flea market and when I turned on the first time, I think the fans never spun up when on load or when the temperatures got higher.

I think BDAqua has a liquid cooled Power Mac because it says "CPU A Pump"

Should I get some hex extensions and continue getting to the Power Supply/ Back of logic board or just leave it alone?

I don't know what is wrong with this computer. The fans should spin faster than BDAqua's readings when those are at 127º when mine are at 151º when playing Minecraft 1.5.2 on Java 5 (I tried to get SE6 to work🙂.) Is it a defect or a CPU/ Logic board/ PSU problem?

Also, the hard drive has been making nosies like its caching or constantly writing something, even the second the hard drive turns on. The fans also spin down to very slow speeds (499, 515 rpm for CPU A,B Intake+Exhaust fans) before logging in, loading login window. I appreciate all your help!

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Answer 6

Drew Reece

Level 6

10,684 points

Feb 16, 2016 10:57 AM in response to Community User

I'd consider clean install on a new partition - it will get your edits to the Apple kexts out of the way, it probably is hardware as BDAqua is alluding to but you can rule out software if you want.

Apologies if your 'Re-installed Mac OS X' means you already erased the HD. 'Reinstall' may not be the same as an 'erase & install'.

Safe mode will disable non-Apple extensions, that means you cannot use iStat - look at your fans & judge the speed to see if you notice any difference.

Try safe mode if your Mac doesn't finish starting up - Apple Support

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Answer 7

Drew Reece

Level 6

10,684 points

Feb 18, 2016 1:40 PM in response to Community User

lazerpouf wrote:

OK, thank you.

I am trying to get the fans to spin up faster but could it be a hardware problem?

499/515/800 rpm seems slow for a hot G5 CPU. Any way to speed them up?

Heat your room. The SS says 77ºF/25ºC is the max room temp for thermal calibration, get close to that temp in the room.

Higher ambient air = less cooling.

Less cooling = more air needed over the heat sinks to maintain the same temp.

Load the CPU's to max (in high performance mode) & leave them running for a long time.

You have seen these fans spin at max when you did the thermal calibration - you said it was loud.

lazerpouf wrote:

No, they do not spin up when at the Startup Manager.

But they do spin up to max when in ASD or Single-User Mode. 🙂

(It's really loud)

They are spinning fast when at the Startup manager.

Your hardware is not incapable of spinning the fans at high rates - it seems like it just doesn't feel like it is necessary when the OS is running.

The SS mentions that fan management is not used when no OS is running - it should run fast at that point as a precaution but you don't have a way to see the fan speed when running ASD.

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Answer 8

BDAqua

Level 10

250,379 points

Feb 16, 2016 10:29 AM in response to Community User

Fans way too slow, temps way too high! 😟

AHT won't help, but ASD 2.6.3 is used for setting & recalibrating the fans, sadly it was never available to the public.

Is the LCS leaking?

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Answer 9

Drew Reece

Level 6

10,684 points

Feb 16, 2016 3:42 PM in response to Community User

I think the red LED is just a warning, search apple.com for more info - I recollect a document that explained it, but it has been a while since my G5 worked & I can't summon up a URL, sorry.

The fans speeds seem low to me and the temps look high. I'm surprised Minecraft runs 🙂

What did you run on ASD? It can calibrate the CPU's, did you actually do that or any of the other routines?

Have you looked for dust bunnies & cleaned it out?

P.S. Doesn't this model have a clear plastic cover inside the door? Removing that was a sure way to get the fans to go to max for me, there was a reflective sensor at the bottom if I recall correctly. Does it have any effect if you remove the door & cover when running?

Step 3 picture #2

https://www.ifixit.com/Guide/Power+Mac+G5+Late+2005+Backup+Battery+Replacement/6 260

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Answer 10

Drew Reece

Level 6

10,684 points

Feb 16, 2016 5:28 PM in response to Community User

I don't know if the thermal calibration would help, I was wondering if it was a recent thing that made this happen but that is not the case.

The check LED sounds fine since it goes off.

You may need many hex extensions to reach those CPU bolts 🙂

A PRAM battery may help, but it seems unlikely to cause this.

What model are those readings from BDAqua?

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Answer 11

Drew Reece

Level 6

10,684 points

Feb 17, 2016 7:20 AM in response to Community User

Sorry I missed the 'CPU pump' in BDAqua's post. It's comparing Apples & oranges 😟

I had an early 05 dual 2.3Ghz model which died about a month after Applecare ended. I don't know if I have any old temperature readings around, I'd need to check old backups, I'll look at the weekend, but I suspect I can't read the format that Bresink's Hardware Monitor uses.

See if you can find some other temp figures for that model on the web.

If it has been running happily for a while why mess with it? How much have you used it?

Linux can be bad at reading Mac temp sensors - sometimes this will result in them being on full blast constantly. They have got better at including drivers or kernel patches to support them.

Check the read me that came with the ASD disk. See if you want to recalibrate (do you think it was done right first time?).

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Answer 12

BDAqua

Level 10

250,379 points

Feb 17, 2016 9:59 AM in response to Community User

Seems it must be the Logic Board, but one last long shot...

Does it boot into Open Firmware with CMD+Option+o+f ?

Type these commands at the prompt...

reset-nvram (press Enter)

set-defaults (press Enter)

reset-all (press Enter)

https://www.powermax.com/product/pow-t52695

https://www.powermax.com/product/pow-t58139

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Answer 13

BDAqua

Level 10

250,379 points

Feb 17, 2016 11:08 AM in response to Community User

Also the hard drive is making a constant weird noise every second (not grinding) and no activity shows in iStat Menus.

The fact that it doesn't show activity to me would mean that the Disk itself is having problems & without OS interaction is trying to correct it.

Those temps °F. or °C. ?

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Answer 14

Drew Reece

Level 6

10,684 points

Feb 17, 2016 4:35 PM in response to Community User

Where are you getting the hardware monitor installer from? What version? It seems like a generic 'this app is mangled - reinstall' error to me. Did you get the old version?

http://www.bresink.com/osx/LegacyProducts.html

I thought your Mac was OK now? The temps reported earlier look OK, it is running 'really loud' which seems appropriate - these machines were really loud when in ASD/ AHT.

Startup manager may not spin the fans at full blast, I can't recall them being too loud at that stage.

Can you boot normally & watch the temp & fan values? Use iStat if hardware monitor won't work.

If you want to stress test the CPU's use this…

http://osxdaily.com/2012/10/02/stress-test-mac-cpu/

See if the CPU's ever go up to 151ºF like before.

lazerpouf wrote:

Also, the computer has a shutdown delay; before when it shuts off. Could that be logic board related also?

Hmm, possibly or it could just be how +10 year old hardware operates. I also see delays on shutdown sometimes on an Intel Mac Pro. So long as it boots who cares?

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Answer 15

Drew Reece

Level 6

10,684 points

Mar 2, 2016 2:25 PM in response to Community User

BDAquas results are from a liquid cooled Mac. The results you found earlier are from a liquid cooled Mac. Both list 'CPU Pump A'.

I don't think these models are suitable for comparing. The heat sink is different, the CPU's put out more heat on LCS models…

You haven't managed to see results from the same model yet, so unless I am missing something your figures are mostly guesswork as to what is 'normal'.

I just found this…

http://forums.macrumors.com/threads/dual-core-g5-temperature.171145/

What is your room temperature like? A cold room can cause more efficient cooling, it's freezing where I am so my computer fans don't spin much until the heating has got the room above 22ºC or I am really loading the CPU & GPU. BDAqua's air inlet is around 23ºC, any idea on your room temp?

Load up all 4 CPU's & see if it the temp goes high, the fans should begin to cool it. It will shutdown unexpectedly if the CPU's get too hot!

The only way I know to reduce CPU temp on G5's is via the 'Reduced performance' setting, I think it is in the Energy saver section of System Preferences. I don't recall any third party tools to increase fan speeds on PPC (SMC fan control is Intel only).

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