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[indibil]

Just mainly out of curiosity and for the on-going record here, Jubadub… what is the exhaust air temperature of your Mac mini, measured under the following conditions?

1. Cold booted with OS 9, with the mini @ room temp. (And what temp is that?)

2. NO applications running and with only your desktop displayed on your monitor. VGA or DVI.

3. THE exhaust air temperature measured at / after 10 minutes of runtime? Idle, under no-load.

All assuming that your mini has had its’ heatsink re-pasted within the last 2-3 years and that you are likely booting from an mSATA or SSD? AND that you are not running some HDMI routine as a monitor.
And for those reading along here that don’t know if their G4 Mac mini has EVER had its’ paste renewed… perform the same temperature test as described above AND I’ll begin yet another topic for those temperature test results to be shared. And I’ll update this post later with a link to that new topic.
Recently, Wozniattack (and others) have suggested the need to also replace the mini’s GPU thermal pad - and this might be even more important to consider, especially concerning your statement that “The SIMS” is one of the heaviest (i.e. “most intensive” CPU & GPU stressful?) games that will run under Mac OS 9.

AND while Bolkonskij’s 1.42 GHz Mac mini came equipped with 32 MB of DDR SDRAM, your 1.5 GHz mini has 64. Perhaps also of some relevance in this situation?

I’ve asked Bolkonskij to provide same exhaust air temperature reading before he attempts a re-paste, and even if he has no video display except for a grey screen. Because how “no-load” can you get? Of course if his fan is now (soon after boot) running at full speed - I’d skip his ten minute test and re-paste pronto.

And then there’s always a monitor failure to consider too, I suppose.

Hate to see any G4 Mac mini falter and fail.

aBc, as Bolkonskij suggests, it would be good to publish more results. Do you still have the photos I sent you months ago? You can post them if you'd like; I can't find them. I did a quick test.

Maybe my test was in a 2GHz Mini G4.

[aBc]

Well Bolkonskij, your results are very interesting. Have you ever renewed the heatsink paste before OR - know if someone might have done so before you? I ask because I re-ran tests here last night under a  similar ambient room temperature (of 65˚ F) and arrived at very similar readings. Same type of sensor probe as yours, just inserted 1 inch deep into the vent. Check my T1 sensor readings below. Yours are noted in Blue.

                       

The T2 sensor readings above are from an un-sheathed metal temp probe, also ran alongside the T1.





Now, why didn’t mine equal that 84˚ (@10 minutes runtime) which I have been screaming about as… “the sweet spot”? Well, I’m going to lay blame with the ambient air temperature. *Cooler than my original findings (from 2023) when the ambient temperature was 76˚ F. However, now still much closer to 84˚ than to 100˚F.

Seems that ambient room temperature air of 64˚ to 65˚ being drawn in and blown over a G4 mini’s heatsink might just result in lower temperature readings? And maybe your paste is fine? I’d still like to see pics of your heatsink and the paste when you remove the heatsink AND a clear pic of the die itself, once cleaned. Just to see if there is any evidence of it ever being a ho-lotta-hotta.


Bolkonskij, have you tried resetting the PRAM? Or once you remove the cover, reset the PMU before even removing the heatsink. OR before any of the above, try booting into target disk mode (holding down the “t” key at boot) just to see if you might get that moving firewire icon on your screen. If not, then the PRAM… and afterwards, maybe the PMU?


Yes indibil, I’d like more results from all G4 Mac mini users… if for nothing more than those individuals getting some sort of bearing on the condition of their heatsink paste. Sounds like another tangential topic that I have been working on that would provide a place for such temps to be posted.

*Also indibil, yes I think your readings were from an “overclocked” G4 mini. AND after our recent discussion concerning your heat-shrink wrapped, metal probe and the possible effects that ambient temperatures can have on more accurate temperature readings, I still have not yet tested insulating the shafts of any long metal probes from ambient temperature interference. Unsheathed shafts do make a difference. [See T2 sensor results above.] Question is, how much of a difference and would foam, partially encased shafts be better than your heat-shrink approach?

As always, more tests!

Best of luck Bski. 

[smilesdavis]

makes me wanna "hotrod" my 1.5 ghz mac mini g4 with a noctua nh-d15

[Jubadub]

@aBc I will have to locate and buy a proper thermometer first... I will keep an eye out for one to try it out. All I have at home is a regular, oldschool, small mercury thermometer, and something tells me it won't work too well on a mini's vent. (Will it?)

[ssp3]

Party pooper here. Wearing EE hat
Guys, any increase of temperature inside the Mini will be compensated by increased speed of variable speed fan until almost the same thermal equilibrium is reached. It is a closed loop system after all. The difference between any two conditions will be so small that it will fall under measurement error. To make the proper comparative temperature measurements you have to use the fan with constant rotational speed and have your temperature probes rigidly fixed always in the same place.
Also, no two Minis are the same. The temperature will also depend on other electronic parts that are mounted inside - what kind of drive, DVD-ROM mounted or not, screw holes covered or not, exhaust intake obstructed or not, extra PCBs, larger RAM and so on. More turbulent or laminar airflow over the heatsink because of those extra parts. Room temperature is only one part of the equation.

[indibil]

I think you're right, and an SSD is especially influential. It tells the motherboard that the HDD is too hot, and the fan speeds up. This happened to me with an M.2 SATA, right after powering on.

Is there any software that can read the fan RPMs on a Mini G4?

[aBc]

@Jubadub, in answer to your question regarding the old mercury thermometer… I needn’t tell you to be careful? But personally, I’d try it. And a couple of things - given that those usually required 3 minutes to measure a temperature, maybe insert it @ 10 minutes and wait until 13 minutes elapses before reading?

Also a warning to keep your eyes on it (perhaps behind a face shield) in case it exceeds 107˚ which was their normal top temp range, when it might actually explode. So, don’t let it get that high / hot. [However, if you’ve re-pasted your heatsink, it’s unlikely that it might get that hot in 10-13 minutes anyway.] One other minor thing is that their low temperature measurable range likely may not register at, or even below 76˚.

I no longer have one of those mercury thermometers because I’d like to test that too. And given the time, I might eventually try a “related” laboratory thermometer because they have an extended range. (Around $10.00.)

Have also considered the newer, 30 second read-time digital thermometers - but they too have a limited temperature range.

And just as I won’t spend the higher prices for a G4 mini these days, I won’t suggest that anyone spend any money on other temperature meters, but I did find one for about $10.00 less than I paid for a dual meter, which might just suit the purpose, should one wish to purchase one. $18.89

https://www.amazon.com/Thermometer-Thermocouples-328%C2%B0F-2501%C2%B0F-Thermocouple-Temperture/dp/B0D5M27WZY?ref

                   



Still looking forward to Bolkonskij’s findings and any other temperature reports from others that might follow.

Now again, back to testing here.

[aBc]

Digital - exhaust air temperature readings from the seven minis above. ˚F temps first, then ˚C temps.



“Analog” exhaust air temperature readings below, from the #5B mini.



The hacked-up “analog” thermometer placement:



More precisely:



Not too bad for an “analog” thermometer ($2.99) for those of you wanting to check your mini’s temps. And AGAIN, this isn’t so much about the various temperatures you might obtain from cold boot to 30 minutes - as much as it is whether or not your mini meets or exceeds 99˚ F (or 32.7˚C)  within the first 5 to 15 minutes of runtime after cold boot.

Need I describe the cutting / trimming procedure for the analog thermometer? PM me and if there’s enough interest, I’ll post those simple, easy instructions. Or maybe YOU will just get them?

Now there seems to be some question(s) regarding the validity of this approach based upon whether or not the fan might engage higher than basic speed during this test. BUT considering that the temperatures remain steady and so very similar throughout testing and even with different machine speeds and configurations… well (aBc blows raspberry). No increased fan speeds were noted here during all the above tests.

BUT, if your mini quickly ramps up noticeable fan speed soon after boot or during the 30 minute period @idle… well may be time to replace that heatsink paste and GPU thermal pad? Know of a better way to determine this without disassembly of the mini and removal of the heatsink? Please, do tell.

NOTE: #5 here did reach 99˚F at the 5 minute mark and then 109˚F at the 10 minute mark (and no audible increase in fan speed was noted). Quickly shut down and replaced the heatsink paste - to then obtain the temperatures noted above.

[ssp3]

No increased fan speeds were noted here during all the above tests.

@aBc, how did you arrive at this conclusion? Did you measured it?

Well, I did. I pulled out my anemometer and run the test for some half an hour. I was too lazy to run it any longer. No display, no any activity, just Mini connected to power source.
Here are the results. 'Wind speed' directly at exhaust after:
* cold start - 2.9 knots
* after 15 minutes - 4.8 knots
* after 30 minutes - 5.8 knots
(No m/s, sorry. Where I use this tool we measure in knots).
This is indication to me that fan speed varies depending on temperature inside the Mini's case, hence what I said in my previous post remains valid.

@aBc, for your tests to be 100% valid, you have to measure the temperature and fan speed. Either indirectly, as I did with anemometer, or directly at fan with tachometer, frequency counter or voltmeter measuring voltage at fan connector. Then you will be able to correlate those two measurements and arrive at some conclusions.

Or, if you want to get away with temperature measurements only, you have to "hack" the Mini and feed the fan with constant voltage from some other connector/source. This is how they probably did it at Apple labs when designing the Mini and this is a scientific approach. Everything else is just "having fun with my Mini".

Over and out.

[indibil]

Digital - exhaust air temperature readings from the seven minis above. ˚F temps first, then ˚C temps.

Thanks for the job!!

[aBc]

Take a twenty year-old G4 Mac mini that was never designed to run OS 9 - much less run vintage OS 9 games - AND with that increased processing load on the CPU and GPU… just assume that the mini will continue to function… because it simply has so far?

They're just so cute! 
The primary intended aim of the Exhaust Air Temperature, Mini Exercise (EAT ME) was to provide an alternative method to check heatsink paste effectiveness without having to open a mini and remove the heatsink, in order to check the performance of the paste. For some reason, many seem to believe that re-pasting heatsinks in these minis simply isn’t necessary… and then wonder why the mini just ceases to function one fine day. What happened?

Of course, disassembly of the mini - down to the removal of the heatsink is not an easy task, but something that simply should be done if one has never done so before. And most certainly these machines will continue to function with old paste, but for how long? And unless you’ve had one since it was new, you won’t know if this re-pasting has ever been done. So best practice is to perform this task. And especially if you’ve just acquired one at today’s higher market prices.

It’s doubtful that you can still buy one for $25 to $50 - as we could back before 2020. So if you want to protect your now, likely over $100+ investment, you’d better replace that paste. AND if your primary intended use is vintage gaming… also replace the thermal pad under the GPU too.

K.I.S.S.
As I have stated previously, the EAT ME approach can be very useful… unless you have a mini that has already approached the brink of failure with fan speeds ramping up beyond basic idle speed very soon after a cold boot. In which case, there’s your immediate sign to re-paste. No ifs, ands or buts.

Now our esteemed, hat wearing colleague ssp3 has proposed the use of an anemometer to determine Wind speed; in conjunction with exhaust air temperature readings to correlate relation between temp and fan speed. Here’s that offering:

       

What were the readings @ 5 and 10 minutes?
(And was Bolkonskij’s fan speed also ramped up during his most recent test?)

Seems to me that ssp3’s paste has already deteriorated to the point that his mini’s temp diode has signaled the increase in fan speed in order to offset an accelerated internal temperature rise. In which case, I’d say definitely time to re-paste and then check with his anemometer again afterwards. And maybe this time, also include the timed intervals of 5 and 10 minutes (which are critical for the defined EAT ME approach).

AND who knows what his actual internal temperatures were? You can’t go by the temps noted on his anemometer. (See example images attached below.) Must be a pretty hefty temp rise in order to increase Wind speed (fan speed) in such a dramatic fashion.

“No increased fan speeds were noted here during all the above tests.” -aBc

Perhaps I am truly fortunate, because none of the tested minis here ever ramped up fan speed in the manner noted above. Perhaps even my old heatsink paste condition had not deteriorated to the point that warranted an increase in fan speed? Still, using the EAT ME approach… three out of the seven minis here registered temperatures @ or exceeding 99˚F - between, or at, five to ten minutes of runtime from a cold boot. See previous posts / tests.

And one does not need an anemometer to determine increased fan speed from boot. Here, I can hear such a shift in fan speed (especially if from 2.9 knots to 5.8 knots!). AND if bare audible isn’t enough… (1). A small candle placed near the exhaust vents. (2). A stethoscope. (3). A burning incense stick’s smoke. (4). A burning cigar or cigarette. In any case, if your mini exhibits an increase in fan / Wind speed - soon after cold boot, well… time to re-paste. Or suffer the impending consequences.

Watching the wavering flame of a candle, or smoke from whatever… should easily indicate a change in fan speed. In any case, one can determine an increase in fan speed during the first 5 to 15 minutes of runtime, without the use or added expense of an anemometer. (I've used the "smoke test" before.)

Now here are anemometer results from a freshly pasted 1.5 GHz G4 Mac mini. Note the variance between 2.1 knots and 2.5 knots from zero to thirty minutes. (Nothing like 2.9 knots to 5.8 knots.)

       

       Full, original test images attached below.


Too much folderol or hair-splitting minutiae for you?
Just open your mini, check, clean and replace your damned heatsink paste.

Unless you’re quite simply more comfortable with this:

“The most likely cause of thermal issues would be twenty years of dust blocking airflow. When you couple cleaning the machine and replacing the HD with a lower power SSD I am already improving the thermal situation on all of these machines.”

New GPU thermal pad material to arrive here today. So yes… more testing, as I wonder about the relation between an old GPU thermal pad in conjunction with old heatsink paste -  and what effect this might have on the internal temperature, especially for vintage OS 9 gamers. [Combined heat of the CPU and the GPU.]

And finally, maybe it’s just about time for me to test the copper heatsink for the G4 Mac minis!
Well, almost time anyway.

In the meantime, well I’m just "having fun with my Minis”.

You pays yer money and you takes yer chances. 

[ssp3]

Seems to me that ssp3’s paste has already deteriorated..

LOL! It's a near mint, all white, no scratches on PSU, original box, all papers, all adapters, all CDs, never opened, all still original Mini. Got it from a regular user (a lady), not some computer nerd. For a Mini it is near cold and dead quiet.

[aBc]

LOL indeed, ssp3…

Give over Mary, stop trolling. Part of the problem - rather than part of the solution.

Many thanks for helping to illustrate one common mindset often employed to rationalize not checking nor renewing the thermal paste in 20 year-old G4 Mac minis.

A twenty year-old Mac mini (in near perfect, pristine exterior appearance) is exempt from re-pasting the CPU’s heatsink? And also… in addition, that mini originating “from a regular user (a lady), not some computer nerd”.

Well as a friend of mine often says: “Now tell me a Western”.

Certainly your pristine Mini will continue to function without renewing the paste. [But for how long and under what loads?] Even as your anemometer readings already show an increase in Wind speed of 165% @15 minutes and a 200% increase @30 minutes — while SEVEN minis tested here with fresh paste (within the last two years) show a mere .04 knot(s) increase in Wind speed from 0-30 minutes.

Yes, you’ve most definitely proved that your fan is working AND that your paste is not handling basic warm-up temperatures properly (as fresh paste would do) — while running at idle and under no real load. But why have your fan compensate for deteriorated paste when fresh paste could easily provide a basic, cooler running mini?

AND instead of reporting the O to 15 minutes runtime results (1, 3, 5, 10) with your anemometer (which would have helped to define when your fan actually began to ramp up) you, in essence, cherry-picked the “Start, 15 and 30” minute intervals for what seems be dramatic effect. AND in the process revealed that your old paste is definitely not performing as intended.

Outwardly pretty, pristine, or not.

Again, the primary aim of this approach is to provide an alternative to actually opening a mini to visually inspect and change old thermal paste (which one should do anyway). Because no one really wants to do that.

So again, whether or not anyone subscribes to the validity of this testing approach… if you’ve got a 20 year-old G4 Mac mini and you don’t know if the thermal paste has ever been replaced, you might do well to open it up and check - before it actually does become permanently cold and dead quiet. (Especially for you retro gamers.)

“Question. How many of users here had CPU overheating problems with their Minis that were in their original condition, not re-pasted by previous owner? Raise your hand.” -ssp3 10/22/2023

See: https://macos9lives.com/smforum/index.php?action=dlattach;topic=6875.0;attach=15330;image