Released on July 21, 2011. Core i5 or Core i7 Processor. Thunderbolt. This unit is also used to run the Mac Mini Server configuration.

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Should I replace the thermal paste on my mini?

Hi:

My mini is still under warranty as it hasn't been out for very long. This is actually my 2nd mini as I exchanged the first one hoping the 2nd one would run cooler. But they run almost identical. This mini has the discrete gpu thus ~6W idle additional heat to dissipate.

I am irritated that I cannot enjoyably stream Netflix without the cpu die reporting 95C via iStat Menus and Hardware Monitor by Bresink, although it does settle out to ~90C. This i5's thermal limit is 100C. Thankfully the SMC is working as the fan runs at almost full and thus I can hardly even hear the movie. Now I know that the total amount of heat isn't going to change by reapplying thermal compound but I think it might greatly reduce the die temp and thus allow the fan to back off a bit.

The mini is on a metal wire shelf that allows airflow into the bottom intake and the rear cables come down from the top so as to not obstruct the exhaust vent. The room is at 26C (55%RH) and the mini idles (2% cpu) at 71C cpu diode and about 66C cpu proximity with ambient air sensor in mini at 56C.

I recently had Apple fix my MBP6,1 17" as it was also having thermal problems however it took almost a week of *arguing* with Apple to get them to make it right, but now it idles at 42C and never goes over like 86C and it used to hit like 103C. I know the mini won't be that cool but I want to know if it can do better than my current readings? I woud assume do this fix myself as the arguing with Apple is incredibly stressful. Oddly none of the reviewers seemed to mention temperature data? I would be curious to see a picture of the cpu die before you cleaned it off in your tear down if you have it? Oh and if these temps are like clearly showing a problem with my mini to the extent that Apple might listen then please tell me :)

Thanks for any advice / stats you can give. I admit I am a tad scared to tear the mini apart but the needing to know what the temp *could* be is killing me :D

Ryan

[update - AUG 29]

A friend of mine bought a new mac mini (base model) and it runs just as hot. Yet he found a mac mini in an Apple Store didn't run hot. Perhaps some cool units exist? I found that Netflix is just bearable with Plex as it uses slightly less cpu than chrome or safari. Probably will endup getting a ROKU or an Apple TV for the future as the mini just sucks at Netflix. Anyways last night I decided to point a fan at my mini. This drops the idle temp from 70C to ~60C (internal fan chills out too). Kinda annoying having the extra fan noise but helps a lot and makes the top of the mini touchable. So that is my temporary advice. I may try water cooling the top of the mini in the future just to avoid the extra fan noise.

As for repasting I will indeed hold off as that seems like the wise thing to do. Also it seems that the GPU either has hardware problems or is in serious need of better drivers. As youtube videos will get like weird green stuff going on and windows with transparency on my other monitor will get weird crosshatch patterns (concurrent). Thus I want to wait and see if Apple is gonna software update or if this unit has issues. Once all that is sorted out and my warranty is nearing the end I will reapply z paste.

[pictures of mini w/ fan xD]

http://dl.dropbox.com/u/2091843/ifixit/m...

http://dl.dropbox.com/u/2091843/ifixit/m...

http://dl.dropbox.com/u/2091843/ifixit/m...

http://dl.dropbox.com/u/2091843/ifixit/m...

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I'm also tempted to clean and reapply the thermal paste. I got my mac mini server on Saturday and was shocked at the 'tickover' temp and the 'load' temp. I too was seeing temps over 90C but the exhaust cooling air did not feel that hot which immediatily made me think of the themal paste.

I redid the paste on my 17" MBP CD (Not C2D) and cleared out the heatsink from fluffy stuff. That helped!

When I was turning the mini over and over working out how it all fitted together I realised that the intake for the air was only around the rim of the removeable base, it can only have been around 1 or 2mm wide, makes me wonder if that isn't a restriction to the flow. Would be interested in others thoughts.

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It is surprisingly easy to accidentally block that small opening. I got around that with the wire shelving. Although I worry way too many people are gonna have that blocked. As for if bigger opening would help I don't really have any idea. I think it is somewhat designed to channel the air flow so perhaps cover completely off might be worse? I can feel a nice draft near the opening already. Maybe I will try at some point or if you do let me know :) And if you reapply the paste (even a year from now) I would certainly be curious as to your results. I will share mine when I hopefully do it when the warranty expires.

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The tick over is about 4%CPU and the temp is 49C

With 6 instances of yes > /dev/null the CPU settled down to 80% utilisation, the temp peaked at 92C but settled down to 85C once the fan caught up which ran at 5300rpm

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Wow that is really good! Nice work!

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I pulled apart my mini tonight and re-applied Arctic Silver 5. I have only been up for about 2.5 hours and have yet to produce any thermal cycles, but the temperature is already down a good 6 C from before.

The process was utterly painless. For anyone that has taken apart a MBP1,1, you'll know what a joy this model is to work on.

For anyone with a modicum of skill, I would say dive in and remove the standard thermal compound. After AC5 has time to reach its full efficacy, I wouldn't be surprised to see an overall 10 C drop across the board. Even know, the 6 C is very much welcome.

As I write this, it is sitting at steady 46 C. Before AC5, it ran anywhere between 51-54C. I must admit I hesitated, but ultimately, I'm glad I did it.

Preliminary Data

I've had time to gather some preliminary data and run several heat cycles. It's now been about 120 hours since the application of AC5. I've also kept the ambient temperature outside the unit constant (increased at times actually, which made little difference in all honesty), at ~21 C.

Firstly, I applied the paste using the "rice drop" method. I placed a dab in the centre of each diode and squished it using the heatsink pads. I did not spread it (as is suggested by AC) as that leaves room for thinner points and often results in thermal paste leaking out the sides and acting as an insulator (the opposite of what we want).

The temperatures now generally remain at about 44 to 47 C during general use (surfing the web, playing songs in iTunes, mail open, and a few other general miscellanea running). This of course is with the mini outputting to a 23" monitor running at resolution of 2048x1152 pixels and running a secondary HDD (5,400 RPM 500 GB) on top of the primary SSD (so it's tight in there). When the monitor is put to sleep and the system allowed to idle (not sleep, but idle), the temperatures drop to around 41 (after several hours). Depending on the draw to the GPU, your mileage may vary.

During load, the temperature rise is much more progressive. The stock paste saw my mini spike in heat compared to the AC5, which sees a much smoother and gradual progression. The fan behaves the same in both cases.

One thing to note, when the chip is stressed, the CPU remains hot (about 50-51) for a considerable while, eventually coming back down to it's resting temp of ~45 C. I suspect this has to do with the extreme constraints of the components inside. Creating that much heat must bake the system and while the fan can cool the CPU, the other components will eventually heat up as well. Since a 51 C is actually the running temperature, the fans will not remain at a higher RPM to move the heat away, hence the system remains in that state longer). Again, this is temporary and after about 30 minutes of light use, it will subside.

At peak stress, the unit has not pushed past 70 C. The stock compound saw temperatures substantially higher (sometimes in almost 80 C). But I have no yet kept it under sustained load (will update when I reach AC5 thermal efficiency).

Final Stages of Reaching Thermal Efficacy

I have hit the 200 hour mark and have managed 4 full heat cycles (as outlined by AC5). The temperatures remain relatively stable from what was initially recorded. The system remains at ~47 C during light use. It rises to ~51 C with moderate use. I doubt there will be much of a reduction from this point on.

One thing to note. The application of AC5 doesn't necessarily "drop" the temperatures, rather than make the cooling more efficient. It's a bit misleading to claim that the CPU runs cooler because that rests entirely on the cooling system and that has not changed. AC5 certainly smoothens the temperature gradient and allows the CPU to rest at lower temperature, but outside of that, there won't be a miraculous change.

Additional Cooling Strategies

I should also mention that I've heard a lot about people raising their minis to allow more airflow. I put this to the test. I ran the unit raise 30 mm off the desk. No changes to temperature. So I went a step further and pulled the base off. That saw a 2 C reduction across the board. I went another step further and placed a small fan (blowing around 40 M3/H) aimed upwards. Surprisingly that saw no change in temperatures (above the 2 C from having the base removed). My theory would be that the components are so tightly packed and hidden away from the external fan, that blowing a bit of air on them was insufficient. It might be the case that a large fan would see a reduction to temperatures, but I'm more inclined to think that it would require a replacement of the existing fan with something more powerful (I want to look into this actually).

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+ nice addition to your answer. I am sure others will benefit from it.

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I would warn against removing the base completely. This may improve the CPU cooling but I believe that it could harm other components.

I have spent some time following the path of the airflow:

It enters the mac mini around the edge of front section of the base.

It is drawn up through the wifi grill and over the hard drives.

It then goes through the main circuit board and back down to the fan.

it's then sent through the heat exchanger attached to the heat pipe.

If you remove the base the air is no longer forced over the other components in the machine, specifically the PSU and the HD('s)

(Notice the seal around the rear half of the base)

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Although I know zip all about this I'm loving the fact you're trying things out and reporting back. If could upvote again I would..

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Thank you everyone for your accolades. As this is my workstation, I wish I could provide more scientific data, but I just can't make it the perfect testbed as I'd like it to be.

@Titanium Jones,

You seem counter your own argument by stating that removing the base would help cooling, but then pull a 180 saying the removal of the base would no longer force air through the unit ;)

But you do raise an interesting point. When I removed the base, I simply stuck a fan under the unit, dowsing the components with air. What I perhaps should have done was use the Venturi system and focus it to follow the current path. This would require manufacturing a "turret" of some sort to focus the air, but shouldn't be that hard.

Ideally, what I'd like to do is make a base that replaced the current one. A new base that houses an ultra quiet fan and helps the current cooling system.

Thank you for your input, it has made me rethink things.

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I'll try to explain what I mean. if you remove the base completely, you will reduce the resistance to flow on the fan thus allowing more air through the fans and the heat exchanger and therefore more cooling to the CPU and GPU. If you look carefully at the base, it is divided into two sections, one at front and one at the back. The flow path is to draw air into the body of the computer at the front of the base and pass it over 'other' components before it reaches the back section where it goes into the fan impeller and is forced out the rear slot. By removing the base completely you remove the first part of the flow path of the air. This could result in the 'other' components not getting sufficient cooling. To summarise: Removing the base may improve cooling to the CPU and GPU, but will reduce cooling on the rest of the system.

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The temperature spike during Netflix use is normal. As far as the thermal compound goes, generally Apple uses cheap compound and it's usually applied very poorly and this makes the heat problem worse. Being that you are under warranty, I'm a little hesitant to recommend re-applying the thermal paste as this isn't a user friendly repair/ alteration. But I can tell you that using Arctic Silver 5 and applying it correctly made a -6C difference in my Macbook. I was not covered by warranty so I went ahead and did this myself, but I can't recommend you do this and void your warranty in the process.

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Aye. Thanks for the data and the sound advice ;)

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OK,

I did it!

I popped out the system board and removed the heat-sink and as expected, big gobs of grey paste. I cleaned up both the CPU, GPU and heat-sink with IPA (alcohol not the beer) then applied the Arctic Silver.

There isn't a specific guide for the Mini Server Mid 2011, but this one was pretty close and I used it to guide me.

The only differences I found were the position of some of the screws.

Things I learned

  • Removing the wired connectors, you must pull UP not in the direction of the wires or the gold contacts pull out!
  • The power connector is pretty stiff but comes off with little or no issue
  • The T8 sprung screws holding the heat-sink down have pretty shallow heads, so make sure your screwdriver is in good condition and the tip is not mullered
  • I don't have a 'special' tool for removing the board. I tried with 2x screwdrivers, as I had read, that didn't work for me. I found that some gentle pressure on the front edge of the board pressing against the round opening was enough to get it to pop out, but I had to remove the top (bottom) drive to get access to the board edge.

As previously mentioned, this, in theory, will void your warranty. But if you do it right, no one will ever know, unless of course you balls it up!

My mini is on the desk and 'old' style mini hard drives are stacked on top of it. I was worried about pressing the air intake closed and so have propped the front of the mini server with 2x rubber feet, infact each of the devices are propped up with rubber feet to allow air flow around the devices.

Lastly I added Fan Control pref pane to jack up the fan speed a bit, still got it set slow to keep the noise down, but its slightly faster.

Screen

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Whoa you are a brave dude! Very nice "Things I Learned" section, that I bet will come in handy when I try it in the future. Your screenshot link isn't working. What sort of differences in temperature are you seeing (without custom fan control of course)? I would be interested in your idle temp i.e. less than ~3% cpu usage and the highest temp you see? You could always open 4 terminals and run "yes > /dev/null" in each of them (and wait for it to stabilize). Either way very cool and thanks for reporting back :)

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Fixed the link.

I'll get temp @ tick over and full load for you tonight.

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replacing the heatsink's interface reduced my mini cpu temp to 55 degrees c idle (down from 65~70 C) and it rarely tops over 85 degrees C with plex running. I used Arctic Silver 5 and it was well worth the effort. My mini is not nearly as well vented as yours, in fact it pulls in a fair amount of heat from my receiver. Considering the environment, the AS5 dropped the operating temperature more than 10 degrees. Hope that helps.

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Macmini 2011:

  • 8GB ram
  • 60GB SSD
  • 1 TB WD HD

:::::::::::::::::::::::::::::: idle load :::::::::::::::::::::::::::::::::::::::::::::::::::

Treatment I:

condition 1: flat placement on class surface. (horizontal)

  • idle temp (out of the box) 69.3 degrees C (on average over 10,000 samples taken over 2 days)
  • Ambient air temperature 22.6 degrees on average over testing period.
  • Case temperature: 43.4 degrees measured with ON-409 and ON-909 Series Surface Thermistor Temperature Sensors placed at positions 3 cm from each corner on the top of the mini. 5th sensor placed just below the apple. Hotspots verified using thermograph. 1,000,000 readings taken over 2 days.

condition 2: Mini placed (vertical) in a NewerTech NuStand Alloy

http://www.geeky-gadgets.com/wp-content/...

repeated tests in treatment 1

results:

  • ambient air temperatre 21.9 degrees C
  • idle temp 64.1 degrees
  • surface temperature 38.9
  • ambient air temp found to be insignificant (statistically)
  • Data fed into matlab and processed in all cases

Conclusion: mini orientation has a significant impact on operating temperature possibly due to the flat surface area and the pattern of air movement created when operating. Eddies form on the surface producing a boundary layer impeding removal of heat. In the upright postion, formation of eddies are minimized allowing for convective currents to dissipate heat more effectively.

Treatment II

  • removing and replacing thermal interface with Arctic Silver 5 via the line method.
  • 200 hour break in period with 4 cool down cycles each 12 hours in duration.
  • repeat procedures in Treatment 1.

condition 1: (horizontal)

  • Ambient temperature 23.1 degrees
  • Idle temperature 47.2 degrees average
  • surface temperature 37.4 degrees average

condition 2: (vertical)

  • Ambient temperature 22.6 degrees
  • Idle temperature 45.9 degrees
  • Surface temperature 38.1 degrees

Conclusion: The internal cooling system's efficiency was able to keep the mini's temperature stable in both the vertical and flat orientations. Although we saw 1.3 degrees difference between the positions, the orientation was not significant at idle processor loads, thus it made no difference. Temperatures did not reach high enough levels to allow convective passive cooling to have an effect.

::::::::::::::::::::::::::::::::: under load ::::::::::::::::::::::::::::::::::::::::

Treatment I (Stock thermal interface) 4 instances of yes > /dev/null

condition 1: (horizontal)

  • ambient temperature 23.2 degrees
  • processor temperature 98.1 degrees
  • case temp 67.9 degrees

Condition 2: (vertical)

  • ambient temperature 22.7 degrees
  • processor temperature 92.1 degrees
  • case temp 61.9 degrees

Treatment II (AC5 replacement interface) 4 instances of yes > /dev/null

Condition 1: (horizontal)

  • ambient temperature 23.7 degrees
  • processor temperature 88.1 degrees
  • case temp 55.8 degrees
  • fan speed 5430 (average)

Condition 1: (Vertical)

  • ambient temperature 22.5 degrees
  • processor temperature 86.1 degrees
  • case temp 35.2 degrees
  • fan speed 4450 rpm (average)

Conclusion: Mini orientation had a small effect on processor temperature between the two position as the efficiency of the active cooling system was able to keep the mini within 2 degrees between the two conditions after AC5 was applied, indicating that active cooling had a significantly greater impact (statically) over passive cooling. The remarkable drop in case temperature seen in both idle load and max load demonstrate that orientation of the mini reduces the work load on the active cooling system as seen in fan speeds resulting in quieter operation. A combination of orientation and thermal interface placement appears to have the greatest effect. Temperature spikes where all seen initially before temperatures normalized.

Running plex with sample reference 1080p mkv video saw fan speeds average out at 2297rpm and cpu temperature average 81 degrees C. More testing is required to verify these numbers, but since I'm perfectly happy with the results, I'm not going to go through any more trouble with this.

Before you comment that I have way too much time on my hands, note that I'm finishing up my masters in engineering and this was simply an exercise in curiosity. The experimental design could be more controlled, but its only a macmini.

Errata

I don't see any issue with the cooling system once the thermal interface has been replaced. Drilling holes in the case does little to improve airflow IMHO and only compromises the integrity of the case. Properly applying AC5 should be sufficient. Measuring the airflow volume with and without the bottom attached yielded minimal flow rate increases which where measured and barely detectable with a research quality flow meter. Perhaps (if one was inclined), adding a thermoelectric peltier cooler would be a more viable option if you're intention was to drop the temp to sub 40degree C levels.

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Fantastic experiment. Good to get some REAL data to back up what I saw! Thanks

B.Sc. in applied Physics

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Search on macrumors for my posts: ( primarily http://forums.macrumors.com/showthread.p... )

Drilling the ventilation holes hardly made a difference at lower speed however I am under the impression that it makes a difference at higher speeds. (used to be involved in electronics and have a drill template to create evenly spaced holes)

Since the 2011 has more often higher fan speeds I consider air filtering a welcome addition (see my other posts on this subject). With overhead lighting (ceiling lights) the filter is not even noticeable. Less dirt buildup internally = better cooling. No dismanteling = no warranty invalidation.

I've also a post on references to safe operating temperatures and running this machine above 80C is not advisable, it will impact reliability. ( http://forums.macrumors.com/showthread.p... )

Increasing the idle fan speed to 2200 rpm gives it about the same idle temperature as the 2010 mini. I am only running Windows 7 (I know) and am using MacFan0_65 utility to set the fan speed after startup. Wrote a few *.bat files and have shortcuts on the desktop to set the speed to 1900 / 2100 / 2300 plus one for checking the temperature. Initially I could not live with the 2011 upgrade but now I can (need the improved data throughput from Sandy Bridge)

I love the Mac mini (especially the 2010) since there is no equivalent quiet, same small form factor PC.

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Errata: No dismanteling => No dismanteling for cleaning once a year

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I am running Windows 7 and on both the 2010 and the 2011 Mac Mini I find that the fan kicks in at a higher temperature than under OS X. This makes the situation worse for those running Windows.

Initially I drilled a series of 1/8" holes in the bottom cover plate in the area above the grill surrounding the WiFi antenna. I've have enlarged these now to 11/64" but this makes the placement of some rubber feet critical since the bottom flexes a lot more which was not the case earlier on.

I get the impression that at 2300 rpm the front of the Mac Mini is cooler than at the back. This leads me to believe that the body plays a large part in the (passive part of the) cooling.

The 2010 Mac mini uses approx 8 watts at idle and the 2011 i5-2530M about 15 watts and imho the cooling system is not sufficient enough (at idling at least) for the 2011 mini. Something must be wrong with the fan control as well under BootCamp.

I am now seriously considering adding two heatsinks on the outside of the 2011 Mac Mini ( http://www.aavidthermalloy.com/cgi-bin/e...).

I intend fastening one on each side with doublesided adhesive thermal tape. This should aid in channeling away an additional 10 - 15 watts of heat from the body.

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I did attach with thermal tape two heatsinks of sufficient size to the sides. This kept the case a lot cooler but the internal temperature differences were minimal. In the end I removed these again.

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If you want to cool down your computer I would recommend you add more RAM to your system, if the RAM is overloaded it will heat up your whole computer.

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Ryan C will be eternally grateful.
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