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[fergycool]

Original content of this post moved to:
https://macos9lives.com/smforum/index.php?topic=6875.msg58084#msg58084

Until this post can eventually be deleted, and then properly beginning this topic with the post below from Wozniattack (which should be the first post under this topic).

Apologies for any resultant confusion.

[Wozniattack]

Hi folks,

I recently repasted my mini following this, but wanted to ask about the thermal pad on the bottom chassis for the graphics chipset. Why does no one ever seem to replace it? Mine seems a little gunky looking from two decades, and the service manual states it needs to be replaced if the logic board was removed. Does anyone happen to know the thickness. Can’t find that anywhere even looking up the part number.

I’d like to give the mini even more life, and I use it to play some classic games also.

It looks about 0.5mm, but in the service manual the photo appears 1mm nearly.

[aBc]

Sorry.

I’m 600 miles from my calipers @ present but I do just happen to have one of those pads stuck to the top of a bottle with me. (Don’t ask.)

So if I had to guess, I’d say much closer to .5mm / than to 1mm. AND I’ve never replaced one either… on the six minis that I still currently have (600 miles away). Of course, I’d be more concerned about this IF I didn’t have all of the screws that actually hold the mobo in place.

*And ahh... I think Ninester replaced his back in 2019 with this:

https://www.amazon.com/gp/product/B00UYTTLI4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1

See his post: https://macos9lives.com/smforum/index.php?topic=4937.msg35828#msg35828

[Wozniattack]

Sorry.

I’m 600 miles from my calipers @ present but I do just happen to have one of those pads stuck to the top of a bottle with me. (Don’t ask.)

So if I had to guess, I’d say much closer to .5mm / than to 1mm. AND I’ve never replaced one either… on the six minis that I still currently have (600 miles away). Of course, I’d be more concerned about this IF I didn’t have all of the screws that actually hold the mobo in place.

*And ahh... I think Ninester replaced his back in 2019 with this:

https://www.amazon.com/gp/product/B00UYTTLI4/ref=ppx_yo_dt_b_asin_title_o00_s00?ie=UTF8&th=1

See his post: https://macos9lives.com/smforum/index.php?topic=4937.msg35828#msg35828

I truly appreciate it. It’s been so hard to fine information on it. The few places that sell the original Appel pads want over $50, not including shipping and customs to Ireland.

I’ll likely replace mine with the GELID extreme 0.5mm pad then, it’s good enough for overclocking VRMs and RAM on the RTX 4090, should do the mini well, and rather cheap here on Amazon.

One suggestion I got off ifixit was to stack business cards next to the pad to try and gauge the height, as you’re the first one to have one to hand!

[aBc]

THANK YOU for the mention of the GELID extreme 0.5mm pad as a possible replacement.

[Wozniattack]

THANK YOU for the mention of the GELID extreme 0.5mm pad as a possible replacement.

The Gelid Extreme pads are 80x40mm, and come in 0.5, 1, 1.5, 2, and 3mm sizes to just seem the best option. The reviews I saw of them dropped VRM, and memory hotstops by up to 20 degrees. Should be well worth it, and a single pad could be used on a few Minis then.

I’ll get the pads ordered end of the month and report back.

[n8blz]

Hi folks,

I recently repasted my mini following this, but wanted to ask about the thermal pad on the bottom chassis for the graphics chipset. Why does no one ever seem to replace it? Mine seems a little gunky looking from two decades, and the service manual states it needs to be replaced if the logic board was removed. Does anyone happen to know the thickness. Can’t find that anywhere even looking up the part number.

I’d like to give the mini even more life, and I use it to play some classic games also.

It looks about 0.5mm, but in the service manual the photo appears 1mm nearly.

I replace these every time, any thermal pad of the thickness already mentioned works. No reason not to since you’re in there, even if pads last a lot longer than paste.

[aBc]

Thanks n8blz. Now I suppose that I’ll need to replace such a pad in order to determine if there’s any temperature difference measured on the bottom? (Still, I place the minis up on little feet to improve air flow underneath, instead of allowing them to rest on their h-o-t rubber bottoms.) Anything to possibly increase their lifespan. (20 more years?)

[Wozniattack]

Hi folks,

I recently repasted my mini following this, but wanted to ask about the thermal pad on the bottom chassis for the graphics chipset. Why does no one ever seem to replace it? Mine seems a little gunky looking from two decades, and the service manual states it needs to be replaced if the logic board was removed. Does anyone happen to know the thickness. Can’t find that anywhere even looking up the part number.

I’d like to give the mini even more life, and I use it to play some classic games also.

It looks about 0.5mm, but in the service manual the photo appears 1mm nearly.

I replace these every time, any thermal pad of the thickness already mentioned works. No reason not to since you’re in there, even if pads last a lot longer than paste.

Truly appreciate it folks. I constantly see folks on YouTube ignore the pads, or say they can just be reused. But after 20 years is well past due.

Thank you especially for the measurements

[aBc]

Hey Ranier!

If possible and you haven’t already begun the process, would you be so kind as to measure and report the exhaust air temperature of you G4 Mac mini AFTER it has been running for 10 minutes and @ 15 minutes (from a cold boot)?

Also: which specific mini? 1.25, 1.33, 1.42 or 1.5 GHz?

AND concerning n8blz’s posts above… could / would you also record the temperature of the bottom rubber pad (closest to area where the GPU would be located underneath) while the mini is still fully assembled (again at the 10 & 15 minutes of runtime)? Even if you don’t opt to change the GPU’s thermal pad.

I’m always in the (what now seems like eternal) prep mode for even more temperature studies of these Mac minis. New pads, heatsink paste and even a copper heatsink replacement.

Thank you!

[Wozniattack]

Hey Ranier!

If possible and you haven’t already begun the process, would you be so kind as to measure and report the exhaust air temperature of you G4 Mac mini AFTER it has been running for 10 minutes and @ 15 minutes (from a cold boot)?

Also: which specific mini? 1.25, 1.33, 1.42 or 1.5 GHz?

AND concerning n8blz’s posts above… could / would you also record the temperature of the bottom rubber pad (closest to area where the GPU would be located underneath) while the mini is still fully assembled (again at the 10 & 15 minutes of runtime)? Even if you don’t opt to change the GPU’s thermal pad.

I’m always in the (what now seems like eternal) prep mode for even more temperature studies of these Mac minis. New pads, heatsink paste and even a copper heatsink replacement.

Thank you!

Once I order some stuff end of the month, I’ll also get a temp probe. At the moment I only have the cooking ones, and one for human temp.

It’s a good idea, and I’ll see what I can do. I’ll run some dungeon siege for about 15 mins and get temps, replace pad, and do the same.

[Wozniattack]

Just wanted to pop back. I replaced the old thermal pad today, and it was well grumpy from age. New 0.5mm pad working well. I ran Dungeon Siege for over 30 minutes before and after. Old hot spot was 41.2c. Then after replacing the pad is dissipating a little more heat after another over 30 minutes hot spot on base of chassis was 43.3c.

Pretty decent little increase, and some peace of mind. The photo is the old pad on top of the new one before I took its film off. Can see it was old one’s top was rather dry.

The new pad was 80x40mm, so just used a craft knife to cut it.

*The second image below (the .png file) added for those with smaller monitors. -aBc

[aBc]

Finally got back to this after Wozniattack’s post above concerning the old thermal pad replacement in the G4 Mini. And I finally got a dual probe temperature meter to use for the eventual copper vs. normal heatsink comparisons - so I used that here for my baseline temperature results from a 1.5 GHz Mini. AND since I do not have Dungeon Siege to run and monitor temps with, a comparison with W’atak’s temps is sadly not completely valid for comparison. However when (and if) I ever get around to changing out that thermal pad, the numbers noted below should / could be (with temps taken again after a thermal pad change).

It is interesting (to me anyway) that W’atak’s recorded temperatures of 41˚ & 43.3˚C [106.16˚ & 109.94˚F] are so close to the HIGH maximum exhaust air temps that I recorded back in 2023. http://macos9lives.com/smforum/index.php?topic=5955.msg52638#msg52638

“Initially, all tested Mac mini fan exhaust temps (mini case covers off) here reached 84˚ (maximum) soon after boot and remained there steady. With the exception of two Minis here that quickly went to just above 100˚F almost immediately. [There’s a BIG clue.] Renewed the CPU thermal paste and those temps then matched the 84˚. (And all with no White Case adapter covers in place ~ “naked”.)”

Now here today with a lower ambient room temperature AND the mini’s cover-in-place, the max exhaust temp was only 82˚F (after 30 minutes). So undoubtedly, ambient room temperatures have some bearing on all of this too. It’s still quite “Winter cool” here. When my previous exhaust temp tests were done, the room was 76˚F. (Nearly 10˚ hotter.) And really all under no load other than displaying the desktop on a monitor in millions of colors. Baseline testing.

Anyway, ATAB = Ambient Temperature @ Boot. And I used the T1 Sensor taped directly underneath the center of the thermal pad on the rubber bottom of the mini. The T2 sensor was placed inside the exhaust air vents on the back of the mini. Minutes noted are elapsed runtimes after a cold boot...

[aBc]

PART ONE

Location - location - locations…

               
                “Bite down.”

Silly me, I thought that a new GPU thermal pad would decrease temperatures - but as Wozniattack reported, temps do rise with a new GPU thermal pad in place. And maybe that is good news for your GPU’s extended lifespan. (This example was tested before install of new thermal pad.)


We’ve all seen those aftermarket upright stands for the G4 minis and even some under tabletop mounts designed to free up available working space? But now, after all of these temperature studies and my own personal view that… G4 mini OS 9 users are now more likely to use them for gaming (and thus increasing & prolonging periods of demand and stress upon the CPU & GPU)… doesn’t increased or more adequate cooling become more of a legitimate concern?

Along the path to determining possible temperature differences between old and new GPU thermal pads… briefly tested standing a mini up on its left side. That places the hottest areas of the mini’s bottom up⬆︎ and off of tabletops and more into cooler, circulating ambient air. (Most internal heat is generated by the CPU and GPU.) *Definitely more effective than my standard bottom application of four, eighth-inch thick feet - one at each corner of the rubber padded bottom - to allow for a slight cooling air gap between the mini’s bottom and tabletop.

Just kept thinking that having a mini resting flat on the bottom rubber pad only contributes to internal heat build up, as heat is then “reflected” up & off of the heated tabletop and sucked back into the mini’s air intake vents by pre-heating some of that intake air, as… it is drawn back into the mini by its little solo cooling fan. (And especially over longer periods of intense & continuous use.)

Thought that Apple might have considered this with the design of their newest minis, but evidently not. They’ve now even eliminated the rear exhaust air vents… and heated exhaust air also exits from the bottom… where cool air is also still drawn in.

(Maybe the newer M4 minis simply don’t get as hot? DieHard, V.Yakob… take some temps will ya?)

   


Anyway, run any video intensive game or video editing / playback programs and you’ll well-know how a G4 mini’s exhaust air temperature and fan speed rises over elapsed runtimes. (Especially if you’ve never renewed your CPU heatsink’s paste.) Even slightly pre-heated air from a flat tabletop could have a bit of a turbo-effect when it comes to internal heat increase and exhaust temps?

Did not test this approach to any great degree, because also wanted to employ the anemometer to measure differences between the old and new GPU thermal pads - and the anemometer requires a vertical upright orientation… (not possible with the mini on its left side). But did take some temperature readings with an infrared laser thermometer at the three points plotted above on the very top image.

Tested running Cinebench 2003, five times successively for 30 minutes. (Still not the same as running a video game - but ample enough for general test purposes and Cinebench 2003 is easy for everyone to obtain.] Can’t find my notes at present but do remember that the “CPU center” temperature never rose above 120˚F and that when it did reach that temp (a few times, after only 15 minutes of runtime) it very soon cooled — as evidently the fan speed increased to compensate accordingly. (Yet another side effect of having renewed the CPU’s heatsink paste.)

In addition, also tested using a 4 inch USB powered fan, at a distance of 10-12 inches from the bottom rubber pad, blowing directly at the bottom of the upright mini. Maximum temperatures then never rose above 110˚F after 30 minutes of runtime.
                                     

Some possible drawbacks that can be imagined from this “left-side upright” approach, are: (1). possibly knocking it over easily — and (2). possible problems with the CD/DVD drive reading or writing consistently?


So, gamers and/or other video intensive taskmasters… maybe shifting the mini up on its left side could be advantageous when long-running apps or vintage OS 9 games… for keeping the mini cooler? And maybe blowing a bit of additional air from a small fan into your mini, might also just be advantageous in the long run?      10 degrees cooler?      *All temps herein are Fahrenheit.


*Never intended to make a career out of this little “mini escapade” but it just made sense to test all of this along the way to FINALLY gauging any differences from a copper heatsink in a stock mini. All tests here performed on a 1.5 GHz mini with an old 80 GB spinning HD (#5B from this group image: https://macos9lives.com/smforum/index.php?action=dlattach;topic=7558.0;attach=15284;image

The one interesting stand from CopperDropDesigns can be also be viewed here in more detail:
https://www.instructables.com/Apple-Mac-Mini-Cooler-Made-with-Drawer-Slide-CNC 

[DieHard]

I will try to at least load a temp program on one of my 2 month old M2 Pro minis;  I am testing my ancient external MIDI gear with the newest version of logic.  I bought (2) M2 pro minis, because Best Buy was blowing them out @ $599 brand new for:

Mac M2 Pro mini with 16GB and 512GB SSD

So, I went from a Mac Pro 6,1 with 64 GB and 4TB NVMe to the silicon... I think they blew these out since they knew the M4 mini would be the favorite in 2025, but the M2 Pro, IMO, is better for audio, with more ports, running cooler, and a better form factor.  So the mini with and external dock that literally fits right under it, cost me $699.  It runs silent, I mean NO noise whatsoever and ice cold, no heat anywhere on the outside after 2 hours of runtime.

Internal SSD Reads and writes at over 3000 MB/s, and the NVMe in the bottom of the dock reads/writes at about 900 MB/s.

[aBc]

PART TWO

tl;dr version?

When you renew the heatsink paste in your G4 Mac mini… also change the thermal pad under your GPU. Ya gotta take the mobo out anyway to remove the heatsink. I used .5mm Gelid GP-Extreme. 120mm x 120mm from Amøzon for around $12.00 - and that’s more than enough to replace the pad in 7 or 8 minis. Of course there are other manufacturers, so your results may vary. AND Wozniattack was correct… your temps will rise as the new thermal pad should conduct heat some mo better.

There, now you needn’t read any further.
Just change the pad when you change your paste. Easy!


Still reading? Be prepared for a great big nothing-burger. You have been warned. It wasn’t enough for me to take Wozniattack’s (and other’s) guidance on this. Oh no, I had to test for myself and if you’re still reading, you can also enjoy in all of the non-fun.

I needed to establish a baseline from which to compare “before and after” results. And instead of using Dungeon Siege, I just ran Cinebench 2003 from start to finish 5 times (30 minutes) because not everyone can easily obtain Dungeon Siege.

Wozniattack previously noted his change from 41.2˚C to 43.3˚C [106.16˚ & 109.94˚F]. A rise of +3.78˚F when playing Dungeon Siege… and after changing his GPU thermal pad. Not all that much difference, really. Right?

Previous wind / air speed measurements were obtained by placing an anemometer right up against the exhaust air vents and without a monitor attached. Well, I needed a monitor attached, on and under a load of sorts, for these tests.


Et voilà… ye olde “Exhaust Air Temperature Duct”.
Now if your eyes are already glazing over, read no further. Still reading? Then onward….




Comparisons between previous wind / air speed measurements and using the Exhaust Air Temperature Duct? (Both below with old GPU thermal pad in place… but with relatively fresh heatsink paste.) A little warmer on the right, but compare the recorded Air Speeds. I chalked up the reduced speeds to the distance from the mini, via the duct. Still usable for intended purposes here.  The temperature differences seem more pertinent, odd as they might be. Maybe partially the result of having a monitor attached and ON? Thermocouple temperature probe still in 5th vent from the left.

Also to consider, left numbers from tabletop flat mini. Right numbers from a mini placed up on #303 cans. (4.625” tall.) Ambient temperatures? 68.1˚F vs. 73.8˚F

           


And now for the really fun stuff. You like numbers? Here’s some more…

             
Top two in the grid are from running Cinebench 2003 for 30 minutes with the old GPU thermal pad. Bottom two are from running CInebench 2003 for 30 minutes with the brand new GPU thermal pad.

I would have thought that the GPU temps would have been higher, instead of the Exhaust Air Duct temps? Keep in mind temperature and air speed fluctuations during the tests. There are more pics attached below.


 Again, all tests performed here with good ol’ #5B 1.5GHz Mac mini and its spinning 80 GB HD. No changing it during all of these tests. And now only one more tear down & setup for the long overdue copper heatsink.  (Maybe another big juicy nothing burger with a stock mini.)

You still reading? If so, don’t fail to check out the attached black & white images below.
Best viewed in the following order… OTP4.png - OTP3.png (Old pad) and NTP4.png and lastly… NTP3.png (New pad).


Maybe this should have all be posted under “Video”?



 Speaking of variances and fluctuations… check the 2.9s red-circled above.
 (And now that’s all about a week of my life and for what real gain?)

Content… brothers and sisters. Content.

AND the fact that if you expect to place high demands upon your G4 mini / heatsink paste and GPU thermal pad it - while you’re at it. Because simply cleaning out the accumulated dust is not Refurbishing it. A baked (yet “upgraded”) mini can still be a dead mini, “as is”. In just a very short time. Just push it a little hard, me mateys.

[indibil]

Thanks for your time and effort on this; it's truly a great effort. I'm going to read it again to thoroughly analyze all the information.

I'm looking forward to seeing a simple comparison with the copper heatsink.

Like

[aBc]

@indibil (and er'body else interested).

Thank you for your kind comments and for taking the time to actually read… and re-read the post. As they say, “the devil is in the details”.

Something was bothering me about the four-panel numeric results last night. The result averages for the GPU Temps, between the old and the new thermal pad didn’t quite look right. The Exhaust Air averages looked correct as they represented a +7.15˚F / +3.97˚C averaged temperature increases.

I should have excluded the bottom GPU 2 Minute noted temps before averaging. Thus, the corrected four-panel image below, with the new (more accurate) averages inside the red rectangle.

                 

And now back to air speed and temperature fluctuations.

Check the black outlined numbers from the Exhaust Air Temp Duct. 10 minutes = 119.5 / 48.61. Then the drop @15 minutes, a slight return rise @20 minutes and then… temperature drops from there @25 minutes and @30 minutes. Safe to assume that the fan speed had ramped up @15 minutes (when I failed to restart the anemometer on time for readings).

And funny that the GPU temps between the old and new are not that much different - AND that heat gains are greater at the exhaust… with the new thermal pad!

Again, perhaps better to have the GPU and the new pad expelling more heat to the exhaust - than not expelling that heat from the GPU - because that can certainly lead to the demise of the GPU.

(Of course, and IF you’ve fresh heatsink paste on your CPU.)

Die mini, DIE!

Again thanks indibil. It might be another day or two before the copper heatsink finally gets a test. (If the good ol’ #5B Mac mini can withstand yet another surgery.)

And @DieHard… go ahead and gloat over the possibly reduced “heat signature” of the newer Mac minis. I am prepared to whine incessantly about this utterly heinous possibility.🤪

Cheers y’all!