Beaglebone Ai Heating Issues

On the subject of cooling there is an ultimate solution, literally, where the entire board is immersed in a non-conductive cooling liquid such as this one from 3M: https://www.3m.co.uk/3M/en_GB/novec-uk/applications/immersion-cooling/

Pump the liquid around the sealed enclosure and through a large external heat exchanger.

Now, where was that reset button? Oh yes, inside the sealed case

Nice! Kind of like a nuclear reactor being cooled : )

I went with some ceramic tiles. Looks a bit like the space shuttle heat shields : )

I'll try powering it up tomorrow. I'm not sure it will be super-effective due to how it was interfaced. It consists of a 60x40x1mm copper sheet, with six 20x20x2.5mm heatsinks20x20x2.5mm heatsinks attached with thermal tape. Then it was attached to the existing heatsink on the BB-AI using more tape. The 60x40 sheet almost does not fit the BB-AI, the plastic standoffs need some dremel'ing with a grinding wheel. I had to do that because I couldn't make the heatsinks smaller, it seemed impossible to cut or sand them, they are really tough. Also, the plastic standoffs needed some trimming in a few places at the junction with the PCB, otherwise they are really close to some components.

A bit sad that I cannot see the guts of the BB-AI any more : (

Good workaround shabaz. Is it working fine on load without a fan?

That is definately a cool look (pun intended). Looking forward to seeing what temperatures you manage to read but I have every confidence they will be in the 'green' band with that arrangement.

I've never used ceramic heatsinks before but I can imagine they are very tough to machine. Probably a diamond coated sharpening tool would help smooth edges or the mating surfaces, something like this from CPC Farnell? https://cpc.farnell.com/rolson-tools/24252/sharpening-blade-mini-diamond/dp/TL16023

Why are the standoffs pointing up and not down shabaz

Did you use https://www.amazon.com/Aikenuo-Adhesive-performance-Heatsink-Computer/dp/B075FR45DV?th=1  or something else as tape?

Hi Rod,

Very interesting tool! The regular sandpaper/cutting stuff was totally ineffective, the grinder attachment just made it red hot : )

These micro porous ceramic heatsinksmicro porous ceramic heatsinks are better and can be more easily cut - and they're a bit more expensive but I think worth it.

Hi Clem,

I used some thermal tape like thisthermal tape like this that I already had (I think this may be the part code).

Good to know, I will try with mine next days. First I will see a real temperature curve while using the board, to have an idea. Then probably adding a small fan is the faster solution I can afford here with the stuff I already have around. Like a CPU fan over the big square cooler. Does it has sense?

It's misuse of those mounting holes : ) I wanted to put a cover with fan glued to it on the underside:

A CPU fan could work well I think! Looking forward to seeing your results! Are CPU fans 5V or 12V? I've wired the fan I'm using (5V) to the connector P9 on the BB-AI, pins 2 and 8 (GND and VDD_5V respectively), I just directly soldered the wires to the underside of the board.

Hi!

No idea yet, but I will try to power up later today, and follow the information people have been posting about how to monitor the CPU temperature.

Hi!

No idea yet, but I will try to power up later today, and follow the information people have been posting about how to monitor the CPU temperature.

I hope this low wattage fan won't affect power adaptor supply. Hoping for the best.

Just noticed there is also a plate behind fan with hole, there might be a problem for air flow. I'm afraid fan might not work at its full efficiency.

These fans are super low power, but don't bet too much on small fans over the desktop board CPU. In that case, they have not serious problems of powering. I am using one of the two macbook pro old model fan that are very low consuming.

Hi!

It's not a very powerful fan, it will just move air at a low rate. A more powerful fan could also be a good idea, but then there could be the need to consider power consumption more (and also noise).

I think you're right, the small holes may not be very good.

The BeagleBone form factor limits the size of the fan mounted on top to 40mm. The GPIO headers are slightly more than 40mm apart. I understand why they wanted to keep that form

factor but in this case I think it was a mistake. I have my AI up and running with the 25mm fan I bought mounted on the heat sink. It is a lot quieter than I thought it would be but I don't

think it is running the advertised 10K RPM. I'm reading a temperature of about 48 deg. C when it is idle and 52 deg. C under light load. In case anybody missed this I posted this earlier:

The next thing I did was go look for where the SoC temperatures could be read and I think I found them several

sub-directories deep in the /sys directory. I do wish that there was a standard directory to put these in as

everybody puts them in very different places in the /sys directory. There are 5 different thermal zones and

each one has a directory in the /sys/devices/virtual/thermal/ directory named thermal_zone0 -  thermal_zone4.

To display the temperature for thermal zone 0 use this command:

debian@beaglebone:~$ cat /sys/devices/virtual/thermal/thermal_zone0/temp

47000

debian@beaglebone:~$

The response, 47000 (your mileages WILL vary) is 47.0 deg. C.

At the time the AI was mostly idle with me on a terminal inside an LXDE window. The temperatures I was

reading were within a couple of degrees C across all the zones. There are many thermal management

configuration files in the thermal_zoneX directories and it would be great to get documentation on what/where

the thermal zones are as well as the thermal management settings used for them.

I wrote a bash script that reads and prints out a "properly" formatted temperature from one selected zone or all zones. From what I saw during testing it looks like zone 2

is the dual core ARM Cortex-A15. It is always the highest temperature by a couple of degrees C. I can't figure out how to make the script available on element14 other

than just paste it in a response so some help there on the best way to do that would be appreciated.

Hi Gary,

I'm using the command you mentioned in your blog post too, and I get similar-ish temperatures (maybe 43-45 degrees C idle, in 22.5 deg C ambient) with fan and heatsinks. I briefly tried running stress --cpu 4 --timeout 60  for want of anything to test the system slightly, but immediately after this stress test, the temperature of the five zones had not risen much (just a few degrees) so it is probably not a good test, e.g. I could be using the wrong flags (also, it won't test anything other than the main cores, and none of the accelerators).

Regarding the script, I think you'll be able to attach it if you've authored the discussion, or definitely if you've authored the blog post. So, (as an example) it should be possible for you to edit your discussion https://www.element14.com/community/message/283031/l/reading-beaglebone-ai-temperatures#283031

since you authored it, and then add it as an attachment. It could also be placed inline, with syntax highlighting (some info on how to do that is here: Using Editor Tools for Blog Posts  )

Another option is github, that entails setting up an account and downloading a tool or to your PC (although there may be a way to directly do it online) and can be done from the CLI too.

For example I'm going to put my notes in a blog post so that I can refer to it later, otherwise stuff will get lost in all these discussion comments, and then if I had a script I could attach it to that blog post.

The 48 to 49 deg. C temperatures while idle I was seeing were pretty much what I expected to see. While testing I tried starting up the web browser and even though the CPU monitor

showed from 60 - 100 % usage most of the time I too only saw a couple of deg. C rise. At one point while the browser was starting up the terminal I was using to read the temperatures

completely froze up solid for 10 to 15 seconds. The combination of these two things made me wonder if some CPU frequency throttling was occurring where it had not before. The

software I am running on the AI was fully upgraded Friday evening and there was a kernel update. Next time I get the chance I am going to look around in /sys to see if I can find where

the core frequencies can be read from.

I tried going back to the discussion you mentioned and attaching it there but I could not find a way to do it. I don't think I tried editing it though so I will go back and give that a try.

I have an account on github but as far as I know it only allows me to clone public projects from it. I would really like to just post it here if I can.

I just tried editing that discussion and I was able to attach the script. Thanks shabaz!

I discovered they have a new default called policy0. Within that policy0, the max GPU frequency is set at 1 GHz value most of the time for both processors. So take that into consideration.

Clem

How's everything going ? Any success?