Heat from the Mac Mini

[N9JIG]

@weaztek I am also wary about artificially messing with the fan controls, not least because it could likely be stressing other components within the the machine. Like you I now run iStat menus and have found it interesting to monitor these things. I picked up this mini a couple months ago and at first it seemed all wrong after using the Mac Pro, but as time goes by I am progressively more relaxed about how the mini operates. It's just different from what I was used to.

Generally I would agree with you except for I have had 3 Macs with heat-generated issues in the last decade. While all three were iMacs, I think the Mini is pretty much an iMac with no display so it is not a stretch to think the same issues would occur.

On my first iMac (24-inch from about 10 years ago with the flat sides and plastic case) after just under 3 years (miraculously just 3 weeks before AppleCare ran out!) I started getting lines across the display and the computer would shut down by itself after a couple hours. They replaced the display, then the graphics card. After neither of these worked they replaced the whole computer..

The replacement was a then-current 27 inch with the i5 with the still current curved metal case. I had this for 4 years and it too started to have heat related issues much like its predecessor. Same display weirdness and random shutdowns when pushed.

I traded that into Apple and got the then brand new iMac 5K in 2015. Lo and behold after 3 years or so it too had the same issues.

As a rule I leave my computer on all the time but let the screens sleep after 15 minutes. I work from home so they are pretty much on and working most of the day. In the evening I often use it to watch TV so they work pretty hard. I am sure this contributes to the issues.

Apple is more concerned with noise levels and aesthetics than throttling and longevity I think. With the Mac Mini, since I have been running the fans at full speed the computer runs very cool, which should go a LONG way to preventing heat related issues down the road. How can that hurt anything?

If they had designed the Mini with better internal cooling (larger capacity fans etc.) and removed the internal power supply and replacing it with an outside brick then the longevity of the computer would be much better and throttling could be a thing of the past.

I also have an Intel Hades Canyon NUC with similar specs and size as the Mini and it runs much cooler and rarely throttles under similar loads with no altering of fan controls.

Other than the fan itself there is little likelihood of stressing any components of the Mac Mini by running the fans full time. Less heat retention/better heat ejection by using higher fan levels can only help reduce heat related stresses on the machine.

 

[weaztek]

I've been using Macs (Power Mac 7200, G3 desktop, Power Mac G5, 24" iMac, 27" iMac, and currently an i5 Mini) since 1995. The only time I had overheating issues was when Catalina OS was first introduced and I was getting kernel panics daily. After several months they fixed the issues and it's been smooth sailing since for me.

 

[ashleykaryl]

@N9JIG I think we can all agree that excessive heat is not a good thing with electronics. One attraction of the move to ARM processors will be lower temperatures and I've heard it said Apple will be able to build super thin computers for this reason.

Regarding the iMac, I had one myself from late 2007 that suffered from heat issues and feel they were fundamentally flawed as a design. After little more than a year the original drive died and a replacement that ran too hot created burn marks on the display inside a week, rendering it all but useless for my work.

That iMac went through three more drives over a few years and I feel pretty certain heat was the culprit, so I can only hope new ones have fixed this, however the experience was more than enough to deter me from buying a new one, which is one of the reasons I turned towards the mini.

I may come back here in six months time and say the mini is a disaster due to heat build up and in truth I've not had this computer long enough to draw any firm conclusions. Most of my work is not putting it under major stress though and as I sit here typing this the CPU is around 45C, while the SSD is under 40C. The top of the case is barely warm to the touch.

When I am building a website, photo retouching or similar it's just not placing the system under much stress and I work on some big project files, so it seems pointless to run certain components like the fan at high capacity full-time. Bursts in temperature like exporting a video tend to be short lived and in those moments the mini fans kick in as required.

Once the CPU demand drops I see the temperature comes down in a few seconds, so if Apple has done a half decent job of keeping the system within safe limits it shouldn't be a problem. We shouldn't read too much into case temperature either if that is an effective means of drawing heat away from components.

At time of writing I can only say I am more relaxed about the heat question than I was initially. There are still quite a lot of old minis in active use and many are worked hard over several years without issue. Certainly the new NVME drives can run very hot due to the speed of operation, however I just did a search and it seems some claim 1.5 million hours mean time between failures.

If we look at other areas of technology from cars to cameras the rate of development in recent years has been astounding, so to a certain degree perhaps new technology turns old theories on their head. I have an interest in vintage watches and its no big deal to have a watch over 60 years old in daily use if it is properly maintained. In about 5 years most of us will be looking at new computers come what may. If we bought an iMac maybe sooner...

 

[grayskyz]

What app are we all using to check our temps?

 

[jayducharme]

I have an infrared laser thermometer and just point it at the top of my mini.

 

[ashleykaryl]

I use iStat menus. It has all sorts of information and I find it very useful.

 

[Erehy Dobon]

Using an infrared laser thermometer to measure the external case temperature is pointless.

The Mac regulates the fan and CPU thermal throttling based on the temperature of one of the CPU cores. This is not unique to the Mac mini or Macs in general. Basically all PCs function this way. CPU manufacturers have a maximum operating temperature for each CPU design.

It's up to the system builder to decide how to balance heat dissipation, cooling system noise (like fans), power consumption, user comfort/safety, etc. This could be Apple, Dell, Lenovo, etc. or independent enthusiasts with their own custom built PCs.

Note that Apple has never referred to their portable Macs as laptops. They have always been referred to as notebooks. They are not designed to be used on a person's lap. Apple deliberately designs their Mac notebooks to run at hotter temperatures, closer to the CPU thermal threshold limit.

The same with an add-in-board GPU card. It's treated as its own system within the PC. Graphics cards have their own fan and cooling systems and all of it is based on the GPU processor core temperature, not the external temperature of the GPU card housing.

It's not like Apple says "this external spot 4.65 cm from the anterior edge of the unit and 5.15 cm from the right edge of the unit should be no warmer than ___ degrees Centigrade." So you can measure it with a laser thermometer. That tells you nothing.

In certain situations on hot days, your smartphone may shut down. It's designed to do that because it doesn't have an active cooling system like a fan.

Even something like a car's engine isn't measured by the external temperature of the hood. Oil temperature is the easiest measure and that's why there's an indicator for it in the instrument panel display (either a gauge or an idiot light). The external temperature of the car hood is irrelevant. Same with the cowling of a jumbo jet's engine.

Anyhow, use freeware utility XRG if you don't want to shell out the ten bucks for iStat menus. They both display the same sensor readings provided by the operating system.

Infrared laser thermometers have their uses but this isn't one of them. It's a safe and geeky way to get a meaningless number.

 

[jayducharme]

It's a safe and geeky way to get a meaningless number.

But I like meaningless numbers!

I do find the thermometer useful just as a general gauge of the case's heat -- because it can get really hot to the touch. I'm not pretending to know the actual CPU temperature.

 

[oppastopa]

If anybody is worried about heat I would encourage finding an external GPU for cheap. I recently hooked up a black magic to my i7 mini and it runs much much cooler and the fans are not ramping up at all.

 

[Erehy Dobon]

But I like meaningless numbers!

I do find the thermometer useful just as a general gauge of the case's heat -- because it can get really hot to the touch. I'm not pretending to know the actual CPU temperature.

OK, that's fine now that you have made that clear.

I just didn't want others here firing up their infrared laser thermometers without knowing that doing so is useless.

I know my Mac mini can get hot to the touch under a heavy CPU workload. Luckily, I find no compelling reason to touch my Mac during these moments. It's a little more than an arm's length away; I actually need to lean over to touch the case.

Remember that Apple is basically using the aluminum Mac mini enclosure as a heatsink. It's supposed to get hot.

I'm more baffled by people who wrap their Mac notebooks with hard shells that often impede heat dissipation. Apple abandoned titanium and polycarbonate as Mac notebook case materials. My guess is that heat dissipation properties was at least one mitigating factor.

 

[ashleykaryl]

If anybody is worried about heat I would encourage finding an external GPU for cheap. I recently hooked up a black magic to my i7 mini and it runs much much cooler and the fans are not ramping up at all.

That sort of makes sense based on what I see with the mini. Temperatures seem to rise most consistently when using Skype or FaceTime and even video playback over any period will raise the temperature somewhat. When using Skype the case becomes very hot after half an hour.

This is not an issue at all with still images and I can work on huge projects in Affinity Publisher with 100+ layers of images without any CPU temperature stress at all.

 

[jazz1]

Would laptop cooling pads help?

 

[ashleykaryl]

In theory yes, but in practice hard to tell. I bought a TeckNet for this reason, because my daughter has one that worked wonders with her MBP. I could test this for longer but it just seemed to extend the time a little before the mini's own fans kicked in under load. The case seemed to become just as hot and so did the CPU when pushed at all.

It's feasible there was a little less throttling under load with the cooling pad but you'd have to run some very controlled tests to establish that and not just one after another. In normal usage a cooling pad only lowered the CPU by a couple degrees, which seemed pretty pointless and just takes up space.

In the case of the MBP the difference is really obvious with a cooling pad, because the fans barely kick in now under load and the batteries seem to last longer. On the mini if you send in more airflow the sensors appear to adjust accordingly, however the end result was much the same from what I could tell. After a few days I just put away the cooling pad.

This was in the summer and I had the window open most of the time. It might be that under different environmental conditions you'd see a different result. In my own experience, I've found that when retouching images, building websites or whatever the mini is very composed and that covers 99% of my usage. If you spend your days editing complex 4K video or rendering files in Maya you may have to think about specific strategies.

 

[jayducharme]

Would laptop cooling pads help?

I have a perpetual calendar in a metal frame. I keep that on top of my mini and it wicks away some of the heat. I don't know how much of a difference it makes, but the metal frame does get warm so I assume it's acting as a minor heat sink.

 

[ashleykaryl]

Aluminium is just about the best material out there for acting as a heat sink and that is what Apple have used for the mini case, which brings us back to the point that we shouldn't necessarily be concerned about case temperature. I know it can be disconcerting but it's sort of designed to do that and I'd far rather have a hot case than fried components.