Throttling?
#1
I'm looking at this board as an upgrade to my Hardkernel C2.
Even with its large heatsink, the C2 reaches 72C under load, in my experience.
(but it does not throttle!)

The Rock 64 has similar power dissipation in the same form factor.
Can anyone recommend case and/or heat sink for it that will keep it from throttling under sustained load?

Thanks!
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#2
(07-05-2017, 10:12 PM)genosensor Wrote: I'm looking at this board as an upgrade to my Hardkernel C2.
Even with its large heatsink, the C2 reaches 72C under load, in my experience.
(but it does not throttle!)

The Rock 64 has similar power dissipation in the same form factor.
Can anyone recommend case and/or heat sink for it that will keep it from throttling under sustained load?

Thanks!

Heatsink, as big as you can put on Wink But more seriously, what sort of loads are you using it for that would need sustained runs? If a case like this were to become available for it, then that would be your best start for passive heat dissipation, but you would still need at least a minor airflow across it as heatsinks only spread heat, they don't magically make it go away.
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#3
Sad 
(07-06-2017, 12:29 AM)pfeerick Wrote: Heatsink, as big as you can put on Wink But more seriously, what sort of loads are you using it for that would need sustained runs? If a case like this were to become available for it, then that would be your best start for passive heat dissipation, but you would still need at least a minor airflow across it as heatsinks only spread heat, they don't magically make it go away.

The problem with that specialized case is that it would prevent a add-on board from being used since the processor is located on the top of the board. It's too bad that the processor was not located on the bottom of the board, so only a thick thermal pad would be needed to transfer heat to the metal case. A plain metal case could be used rather than a custom machined one, and add-on boards would not be blocked. I have seen boards with the processor on the bottom of the board, but not many. Is there any disadvantage to doing this?
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#4
(07-06-2017, 01:45 AM)stephen fleming Wrote: I have seen boards with the processor on the bottom of the board, but not many. Is there any disadvantage to doing this?

Not sure if there is any disadvantage other than the obvious one of heat rising Wink Maybe routing of the traces will be a bit more challenging when they need to access stuff on the other side of the board?, unless they basically flip the board layout over? But I get you point, if you're using the board for anything more than just itself, machined cases like the one I linked aren't possible! Sad Hence the more traditional big heatsink on the CPU (and memory if needed) and fan to cool the whole thing down.
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#5
For anyone looking to find a stick-on heat sink, Digi-Key has a large selection to chose from:
https://www.digikey.com/products/en/fans...geSize=500
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#6
I see two problems with mounting the SoC on the bottom, it needs a special case/cooling solution and you need to have a more expensive process if you want to mount 'heavy' components on both sides of the board during manufacturing (wrt reflow soldering, but also inspection steps).

I use a Fischer 14x14x14mm heatsink for PGAs on my Rock64 at the moment, and during kernel compilation on all cores which takes about half an hour, the temperature ususally does not rise above 70-72C which is still a good margin before throttling starts.

http://www.fischerelektronik.de/web_fisc...ndex.xhtml

They also have more low profile solutions with 6mm and 10mm heigth:

http://www.fischerelektronik.de/web_fisc...ndex.xhtml
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#7
(07-06-2017, 02:08 AM)pfeerick Wrote:
(07-06-2017, 01:45 AM)stephen fleming Wrote: I have seen boards with the processor on the bottom of the board, but not many. Is there any disadvantage to doing this?

Not sure if there is any disadvantage other than the obvious one of heat rising Wink

Perhaps the solution is to leave the CPU on top to allow thermal rising, but place the daughter-board connector on the bottom?
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#8
Hello.
I am doing some tests with the Rock64, and I've just done temperature tests.
With my small heatsink, no fan and a Blender render it reaches above 84°C.
It does not seem to be throttling. What is the throttling temperature of the Rock64?
With my 5V fan it does a lot better.
This is without a case, so if you buy a case, be sure to use a good fan.
Here are my results.

No load no fan : 52°C
Max load no fan : 84°C No throttling

No load with fan : 40°C
Max load with fan : 60°C
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#9
The trigger points for throttling and emergency shutdown/reboot are defined via devicetree, so it depends what kernel/dts you run on your image. Currently the latest ayufan images use

https://github.com/ayufan-rock64/linux-k...4.dts#L604

Code:
&threshold {
    temperature = <80000>; /* millicelsius */
};

&target {
    temperature = <95000>; /* millicelsius */
};

&soc_crit {
    temperature = <100000>; /* millicelsius */
};


The absolute maximum for RK3328 is 125C ...
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