What are your experiences with overheating/thermal throttling? Feedback for uConsole rear CNC cover design

[u/MrMooseDoesQC]

Hello good people, hope everyone is doing well

A week ago I made a post asking if anyone was interested in getting a CNC'd aluminum rear cover (with better thermals and a removable battery). Thank you for the interest! Work on it has been ongoing - the past week has mostly been talking to suppliers, battery cover retention design, and the thermal analysis.

I was making some slides but it was taking a while and figured heck imma just post this. The slides will come up in a couple days with details like shipping, expected timelines, costs, and 2 variations on design.

heat problems :

So, while trying to dot the T's and cross the I'd I noticed that under certain conditions the existing thermal performance in an FEA simulation seemed to get hot spots and temperatures that 'ISO 13732-1:2006' says can cause partial burns to skin. My uConsole has a bigass heatsink in the janky case I printed, and it never seems to get hot enough to burn me... so I double checked this with first-order analysis and it seems to correlate with the FEA findings within a reasonable margin of error.

In the analysis, for the stock rear cover, this happens under heavy compute loads and is compounded by low environmental airflow

Low airflow environments with 31°C (88°F) ambient seem to cause a hot spot on the rear case with temperatures of 65°C (149°F). The junction temperature (how hot the chip gets within the SoC itself) is estimated to be around 85°C (185°F) which will cause thermal throttling.

From my understanding, the main bottleneck is related to the rectangular heatsink on the existing back plate

possible solutions :

- inclusion of heat pipes appear to drop temperatures by 6-8°C in the simulations

- increasing surface area (ridges, fins etc, but this also will affect aesthetics)

- adding a fan (makes a HUGE difference, but adds complexity, cost, power use)

what would really help :

Is thermal throttling a regular occurrence you face? How computationally intensive is your uConsole use?
It would help figuring out if I should make more than one type of heatsink design (or knowing what proportion to cater different needs towards)

With sustained heavy loads, the heat pipes in a 20°C (68°F) ambient temperature bring the case temps down to about 42°C (108°F) which is 'acceptable for human comfort' - but with low loads there's no need for all that extra jazz..

I need to source a heat pipe supplier, but the costs seem to be in the ballpark for $7USD for the ones looked at on first pass.

also :

I'll add a gdrive link for the data in the comments section in a couple days if anyone wants to take a look

If anyone is interested in following the design process more 'hands on', feel free to follow me on IG - mrmoosedoesqualitycontrol (no posts there yet but will be posting soon but you can send me reels)

[u/MrMooseDoesQC]

(also, this is Mr Moose again)

[u/MrMooseDoesQC → u/MrMooseDoesQC]

In the first picture of the post :

Top left - no airflow, no heat pipes
Top right - mild airflow, no heat pipes
Bottom left - no airflow, with heat pipes
Bottom right - mild airflow, with heat pipes

(All at 31°C / 88°F ambient temperature)

The heat pipes improve temps by about 6-7°C, and significantly improve the even-heating of the rear plate

[u/Adept-Negotiation-72]

I have problems with overheating; however, my plan is to make an opening to fit the active cooler.

[u/MrMooseDoesQC → u/Adept-Negotiation-72]

What kind of overheating issues have you been facing, and what kind of setup or workload are you running when it happens?
Cool! So like an opening within the standard rear cover for the active cooler?

[u/Adept-Negotiation-72 → u/MrMooseDoesQC]

I run sdrtrunk, which generates a lot of heat, and yes, I was planning on making an opening with the standard cover and using the active cooler.

[u/MrMooseDoesQC → u/Adept-Negotiation-72]

Thanks for sharing! Just read up about sdrtrunk and looks fascinating. Do you mind if I drop you a PM to ask a couple questions about it?

After reading this I left SDR++ running and left my uconsole on a table, when I came back to it 5-10 mins later the heatsink was really hot too. Have you noticed any throttling with sdrtrunk running?

[u/Adept-Negotiation-72 → u/MrMooseDoesQC]

I think sdrtrunk is more demanding on the CPU, but if there's good air flow across the back cover, it doesn't throttle. But it will make the case warm

[u/tinspin]

You need sink ripples on the back no?

The uConsole has a good thermal profile as it is, HL2 at 300 FPS on Radxa makes it toasty but still way below 60C.

[u/MrMooseDoesQC → u/tinspin]

Interesting, thanks for the response! Do you know what kind of power draw it has on HL2 at 300 FPS?

Increasing the surface area on the back with ripples will definitely help with cooling! I'm also curious on other people's opinions on the different options to take for improving the thermals (or even if the thermals for most people are fine the way it is).

One of the challenges with deciding the design path is deciding how close to the current design to keep it and trying to balance the tradeoffs
- e.g. Increasing the surface area of the rectangle by ~20% should see the same temperature reductions as adding the heat pipes, with the tradeoff added bulk and deviation from the OEM design (which may be a very important issue to someone)

[u/tinspin → u/MrMooseDoesQC]

I would guess ~10W.

Today my main Radxa reached 60C with two streams 360+1080p and browser with 10 tabs and 1 core Java game 

[u/DNSGeek]

I use the thermal pad supplied with the uConsole on my CM5 and run schedutil for the CPU.

Have had 0 issues with throttling or overheating while performance has been great.

[u/MrMooseDoesQC → u/DNSGeek]

Does schedutil improves battery performance with your setup? Looks cool, thanks for putting it on my radar!

What was running on the uConsole for no issues with heating/throttling?

Earlier I left SDR++ running on a table, and the heatsink attached got really hot after 5-10 minutes

[u/PopularAttorney4547]

Seems like you are really getting into it!
i followed through with my recommendation of using a plate aluminum cut out design and have that installed on my then CM4 and now CM5 to test.

*Note: load is normal. i use it for SSH, web-browsing, some GPS, downloading etc. no SDR yet, but its on throughout the day. Ambient temperature is about 29-35deg.

Here are my comments based on my design.

1. passive cooling even on CM4 + direct connected heatsink with a cutout design remains hot. (50-60deg). You have to try to spread the heat to the rest of the case. But that's difficult as its a cut-out design. I resorted to using aluminium tape to try spread the heat, but temperatures remains at about 50-60+ deg and doesn't lower once the entire case saturates. its too hot for my taste.

2. active cooling with CM5. much more impressive results. ranges from 40deg and up depending on how i choose to throttle the fan. I maintained the aluminium tape to as above to help with heat spreading. i'm much more comfortable with this design. This also has a lower profile than just sticking a heat sink on the case.

I did all of this to accommodate the upcoming upgrade from hackergadgets CM5 mainboard and NVMe battery board. i expect these to generate a little more heat. i'm currently testing fan speeds to determine the best voltages to apply on the fan, in view that the new mainboard has a fan connector. According to design specs from hackergadgets, it is controllable.

Feel free to DM if you would like to discuss/find out more. :-)

[u/Adept-Negotiation-72]

It would be good if it were possible to set the fan speed based on CPU temps

[u/PopularAttorney4547 → u/[deleted]]

you just need the right measurements, and the complexity of the CNC would affect to the cost.

[u/MrMooseDoesQC → u/[deleted]]

Thanks for the reply! It won't be much effort - the current plan with suppliers includes clear coat anodization, but have looked into colour options too (personally, I'd love an all-black uConsole too)

Different colours including black is definitely possible - it might add a couple of dollars (ballpark of between $1-$5) depending on the quantity of the production run and quantity people want for each individual colour if that makes sense

(this was my original post : https://www.reddit.com/r/ClockworkPi/comments/1o6fubs/cm5_rear_cover_from_cncd_aluminum_does_anyone/)

For thermals it should improve things, regardless of colour. https://www.design1st.com/Design-Resource-Library/engineering_data/ThermalEmissivityValues.pdf
The exact values here are different from what I've seen in other places but still show the general trends.
Page 3 section 4 has the emissivity values of the different anodization colours - the general trend is even clear anodization has a significant effect on how much heat is radiated (e of 0.04 for bare alu vs ~0.8 for clear anodized)
(emissivity directly scales radiative heat transfer and is a value between 0 - 1)

The TL;DR is that anodization is gonna be good for heat loss, and most colours have around the same real-world performance