Ameridroid Rock 5B Metal Case!

#41

I reckon it would be, but as I mentioned the 0.3mm arrived first, and a single 0.3mm shim didn’t look right (although I may have rushed that step and not fitted the board properly) … I probably should have added that the 0.5mm have NOT yet arrived.

I could possibly test the 0.5mm when they arrive, just out of interest, but it’ll depend on the never-ending battle between time and priorities :wink: . Given the combination of cost, benefit and time I figured that one or both of the shims would probably provide the best result … I’m not sure I need perfection, but I’m sure as hell going to do better than what was provided with the case! There’s probably something to be said for the extra pressure that a larger shim, or combination of shims, might provide … but then we’re stressing the board … hehehe … let’s not go down this rabbit hole!

Check out the difference between the thermal conductivity of copper vs a thermal pad!
The numbers are 398 W/m•K for copper vs 10-14 ish (IIRC) … and the 10-14 is the GOOD stuff!
ie: the copper conducts heat, and a “thermal pad” is an insulator (by comparison).

For that matter, the “thermal paste” is also a thermal insulator (compared to the copper), but should only be the thinnest smear: it’s purpose is more to replace the air that would otherwise be between the imperfect mating of the two surfaces.

#42

That’s what I suspected regarding thermal pads being less efficient than pure copper for heat conductivity.
Best of course would have been direct contact with case heatsink and just thermal paste on top of SOC but it seems they let too much gap in between.
If I have a chance to get that case, I’ll probably use thermal pad first, as I have some to hand and see if I need to improve especially during summer.

#43

I have used a simple 0.5mm thermal pad (Arctic). I have tried to install 2 thermal pad layers (=1mm) but the PCB started to bend a little bit. One 0.5mm pad is just fine in my case (there may be be some production tolerance, it might be different for other)

I did a 100 minute burn @20°C ambient temperature and I have got this:
(so there is 6°C ambient temperature offset compared to your test)

Rock5%20100%20minutes%20burn%20stress%20-c%208
Rock5 100 minutes burn stress -c 8.PNG567×648 86.3 KB

Conclusion:
Don’t bother with messy thermal paste. For such low power consumption, it’s not required, a thin thermal pad is as good.

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#44

I did some Monero mining with xmrigCC for about 45 minutes just to see what the thermals would look like with Radxa’s metal case + thermal pad, and the case got pretty darn hot, and according to psensor, it was at 67 degrees C for four cores, and 64 for the other cores. It was hitting 100% CPU utilization the whole time, and the ambient room temp was 17 degrees C. I’m happy with the thermal performance under those conditions, and I won’t be stressing it to that degree ever again, because it’s not meant to be a mining computer for me.

#45

I’m not sure how anyone gets these things assembled without modification. Regarding the (board-to-backplate) screw head interference (with the itty-bitty “shelf” in the extrusion), I divoted the shelf back to the main surface, gaining nearly 2mm clearance (1mm per side). For folks without a pile of tools lying around, this would be pretty inconvenient.

Checking my moderately large collection of M3 hardware, most screw heads vary between 5.25 and 5.5mm, with some larger. The only smaller heads I found were on sub-mini 120 degree countersunk screws, at 4.75mm. Nothing that would fit.

I also tapped the wee 2mm holes for the backplate-to-extrusion screws to 2.5mm (as the holes were conveniently the correct tap drill diameter) and reamed the backplate holes (very slightly) to 2.5mm, for M2.5 x 14mm screws. I’d have gone to M3, but there’s so little meat I didn’t want to compromise the extrusion, especially since mine is a bit squashed and I have to squeeze it together to assemble it. As for the faceplates, I could re-work them (either drill the screw boss to 2.5mm or trim it), but I doubt I’ll use them.

#46

I’m a little surprised by your 49C temp given the description. Perhaps I have more work to do! Was your test with stress, or something else, and was the case sitting on the universally accepted test bench, hiding with it’s brethren behind the coffee cup, or mounted on a vertical surface in a draft? :wink:

I went the copper shim route not just because I expected (short term) heat transfer to be better, possibly giving lower average SOC temps under normally light loads (hard to quantify+test+compare), but also because I couldn’t justify spending MORE (per unit) on a thermal pad … I’ll be able to use the spare shims for something, right? :wink:

From that point of view, I’d have expected long(er)-term high-load temps to be all in the same ballpark (high 50’s to high 60’s) regardless of the TIM. Maybe, over that (medium?) time frame, the 20C ambient makes that much more difference to the SOC temp?

Speaking of coffee …

#47

Yeah, it must have looked like a good idea in CAD :wink:

I reckon the trick is that the green panels are a little flexible (I assume they’re ABS), and carefully prying all the edges with a small screwdriver eventually frees them, but the problem with that is that I expect that the centre clips will be the first to droop+break from work-stress after frequent removals. I suspect that removing those centre clips would be the best option, and that the only minor issue with that approach would be that the panels are potentially not prevented from bowing after extended misuse.:wink:

#48

It seems to me that this case was originally designed to use a thermal pad, but subsequently it was realised that repeated disassembly would be a problem, so paste was substituted as the cheapest option. Understandable, I guess, but ironic given how difficult it is to disassemble :confused:

The paste alone seems like a very poor choice, given the size of the gap. It’s like using mortar to fill the space a brick would fit! :wink:

That said, I probably wouldn’t have been so offended by the paste if it had been a THICK paste, rather than sloppy.

#49

I have one of the A8 wireless modules so I had to figure out where to put the 2 antennas so I just used some double sided tape and stuck them to the upper part of the front panel. The antenna wires are kinda short but with a little care it can be done.

#50

The idea is get a bit of pressure, so yeah given the gap size, thermal pad seems an appropriate choice. If only I could place the order for that case …

#51

My case didn’t come with a thermal pad or paste, so I had to use a thermal pad I had laying around for an NVMe drive and cut it down to size. It seems to fit properly, and to do its job well enough.

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#52

I can confirm that 3 mm thermal pad is too thick. It will bend the NVME SSD, so i have now ordered a 2 mm.

I have now shaved off some of the thermal pad to use it until the 2 mm arrives. I am kind of shocked by what i see…

It went from 33 Celsius (idle)(without thermal pad) to 24 Celsius (idle) (with thermal pad that is shaved off)

Without thermal pads: Benchmarked it to see the speed (10-30 seconds), it went fom 33 celsius to 34 celsius

With thermal pads: Benchmarked it and it went from 24 celsius to 25 celsius.

And this is ONLY with the bottem part attached to it. So i haven’t put this Rock 5B not yet in the full case.

After about 10 minutes being on it is now on 27 celsius. So i guess for that little amount of money for thermal pads i could say it is worth it with the metal case.

#53

In any case, the green color is too ugly for me. I am looking forward to see something like this https://www.printables.com/de/model/312842-radxa-rock-5-model-b-rock-5b-snap-fit-enclosure made of aluminium.

#54

You are asking for apple like design ^^
I guess they took green to match their logo but I agree it doesn’t look very good.
Still I need a metal case asap

#55

It doesn’t have to be silver. I just like simple designs. It also could be black or white for all I care. I also dislike the cooling fins of this case. It probably does a good job cooling, but will attract dust in the long run.

#56

Wonder what cost it would be to design our own and get it from CNC service.
Here I didn’t buy official case due to additional shipping cost… should have ordered at same time as my board

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#57

I think the case was released a bit later anyway. CNC milling costs will vary. In any case you won’t be able to afford it for just one work piece. You’d have to order 100-1000 at least. Then there is also no good model out there yet. It would take some time to get the dimensions right with all the connectors. Even the case by Radxa doesn’t seem to have nailed it there. So I will just wait until something good arrives. Unfortunately the selection will not be as big as for the Pi. Would be great if the FLIRC or Argon teams would make one.

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#58

It does. I have this setup.

#59

How long did it take to receive your metal case from AmeriDriod ? I have been waiting weeks. The eMMC and Radxa WiFi I ordered also said pre-order so maybe that slows it as well. Or are people getting the cases from allnetchina?

#60

Since my last update I had been testing a 0.5mm copper shim AND “ground” the “CPU Post” to get rid of the anodising. The 0.5mm was CLEARLY too thin, compared to the TWO 0.3mm shims I’d tried previously … removing the anodising probably didn’t help much (up to 100 micron thickness, I’ve read).

A few weeks ago I received 0.8mm shims, and the difference is IMMEDIATELY noticeable.

Under heavy load it takes MUCH longer for the CPU to heat up (both by reading sensors and feeling the heatsink with hand), VERY much longer for the fan to turn on (as a result), and MUCH+MUCH quicker for the fan to turn off after the load is reduced …

Impressive difference for such a minor measurement, to say the least!

So, for GOOD cooling with this case, I’m sure a thermal pad would do the job … but for VERY GOOD cooling use a 0.8mm copper shim (plus MINIMAL smear of heatsink past on mating surfaces) and provided that you can get the “CPU Post” FLAT grinding off the anodising works well. By all means include the PWM fan (internally!) if you want to nudge EXCELLENT cooling :wink: .

I was still concerned about the NVME drive, though, so I’ve added a 1.5mm copper heatsink with some themal pads sticking it the the base of the case … and because the drive is at an angle to the base, I doubled over pad at the socket-end.

With 21 docker containers running, and a system-wide long-term load-average of ~1.2, this results in a bigcore temp under 37°C … a good 5°-6° cooler than with the 0.5mm shim!

[EDIT] Long term running all usual containers, and today (20230205) bigcore is 37.0°C at 26°C ambient.
And nvme-cli shows the NVME drive is stable on 39°C

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