Arathonk
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Raspberry PI3 B+ overheating

Fri Sep 01, 2017 11:24 pm

Hi guys,

I have a Raspberry PI3 B+ Running OSMC running latest Kodi,
Since a update a while back I notice that the PI is overheating, the overheating symbol shows and the case is warm on the outside,
This is happening after the P.O. is running for say an hour,
Only things I do on it are having OpenVPN running and listening to radio/Spotify and streaming series and movies, nothing too fancy.
I guess the P.O. shouldn't be overheating while doing these things right?
I have some heatsinks attached, and ordered new one to try those.

I just installed a fan, it does reduce the heat a little bit but the fan noise is way too loud, you can hear it when watching a movie from 3 meters away, so that's not an option.

What could be the problem?

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DougieLawson
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Re: Raspberry PI3 B+ overheating

Sat Sep 02, 2017 9:22 am

Fans are noisy, even when they claim to be silent. Cheap fans are very noisy because their bearings are cheap crap.

https://flirc.tv/more/raspberry-pi-case-ke
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davidcoton
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Re: Raspberry PI3 B+ overheating

Sat Sep 02, 2017 9:30 am

Welcome to the Forum!

I assume you have a Pi3B, there is no model Pi3B+.
What do you mean by "P.O."?
The Pi3B can get hot when working hard. Make sure it has adequate ventilation -- a closed case will retain the heat. Heatsinks need good airflow to do their job.
Make sure the heatsink are attached with a good thermal paste or tape. Other attachments will be a barrier to heat flow.
A fan is sometimes necessary, it can be connected through a transitor to a PWM GPIO output and its speed controlled by the SOC temperature. This will minimise the noise. Note that some fans are quieter than others, usually bigger is quieter.
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Arathonk
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Re: Raspberry PI3 B+ overheating

Sat Sep 02, 2017 9:38 am

Indeed you're right that's the one,

What pins should I use to make the fan temperature controlled?
I have it now to a ground and a 5v pin,

The case that I have has enough holes in it,
It only gets that hot after an hour/2 hours of video playback or radio,
But is it normal to heat up like that?

I will look into that case, would every aluminium case work as a heatsink like the flirc case?

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davidcoton
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Re: Raspberry PI3 B+ overheating

Sat Sep 02, 2017 9:47 am

I don't see enough Pis to define the "normal" heating. Use Google to search here (use "site:raspberrypi.org") to find other people's experiences.
Similarly to find examples of PWM control of a fan.
The FLIRC case has been well received here, the critical thing is the contact between the SOC and the case.
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Imperf3kt
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Re: Raspberry PI3 B+ overheating

Sun Sep 03, 2017 9:28 pm

You can use pin 12 or 18 for controlling fan speed as those are the PWM GPIO headers. DO NOT plug the fan into these pins, only a transistor. Power the fan via the 5v pin only.

There are several guides on the forums or Google, but in short you need some code to work it as well.
You'll also require a transistor.

Personally I have a fan blowing air over a small 3mm copper slab stuck to the SOC with some thermal grease. I do still need to find a way to secure it, but laying it flat on a wooden surface or cardboard box works fine.

I blow the air from left to right (from the DSI port toward the USB plugs), instead of down onto the SOC. This keeps my (uncased) Pi3B around 30℃ even when I'm really pushing it.

For a transistor I use a NPN 2N2222 MOSFET
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davidcoton
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Re: Raspberry PI3 B+ overheating

Sun Sep 03, 2017 11:02 pm

Imperf3kt wrote:
Sun Sep 03, 2017 9:28 pm
For a transistor I use a NPN 2N2222 MOSFET
Just for the record, and to avoid confusion, 2N2222 is a bipolar transistor, not a MOSFET. No problem using it to drive a small fan, the absolute maximum collector current is 800mA, max collector voltage is 30V.
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Imperf3kt
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Re: Raspberry PI3 B+ overheating

Sun Sep 03, 2017 11:22 pm

Woops, you are right. Not sure why I called it mosfet, it is BJT.
Brain fart?
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jwatte
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Re: Raspberry PI3 B+ overheating

Mon Sep 04, 2017 1:43 am

BS170 is a good cheap MOSFET if you want to use that instead. It's also called 2N7000.

Another idea is to put the Pi on its side, and orient the heat sinks so that the air can flow from down to up in that orientation. (Orientation is impotant for E-profile heat sinks; not important for pin-profile heat sinks.)
If it's in a case, make sure there are plenty of holes in the bottom and top when it's in this orientation.
Heat convection may cause enough airflow that you get the cooling you need. That of course depends on the rest of the surroundings -- if it's behind a heavy velvet curtain inside a small drawer, nothing's going to cool it very well :-)

I wonder what people using HATs do about cooling? I'm going to be running a small neural network on the Pi, and stick a HAT on it for controlling motors and stuff; I don't know how the chips will get cooled in this case, and the NN will use most of the cores with high utilization...

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Imperf3kt
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Re: Raspberry PI3 B+ overheating

Mon Sep 04, 2017 2:00 am

jwatte wrote:
Mon Sep 04, 2017 1:43 am
I wonder what people using HATs do about cooling? I'm going to be running a small neural network on the Pi, and stick a HAT on it for controlling motors and stuff; I don't know how the chips will get cooled in this case, and the NN will use most of the cores with high utilization...
https://i.imgur.com/zLjZw7I.jpg

The fan goes on the right side (don't use a normal fan, use the kind that directs the air to the side, like a laptop cpu fan.)

See the copper heatsink, 3mm tall? Thats about all you should need.
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