0

This question already has an answer here:

I'm putting a Pi in my attic which has, on hot days, an ambient temperature of 45-55C.

A) Will the Pi operate correctly in these temperatures?

B) Will I need a heatsink?

I've read the Pi 3 will throttle the CPU back when it hits 85C. Does the Pi 2 also do this?

marked as duplicate by goobering, Milliways, Piotr Kula, Jacobm001, joan Feb 6 '17 at 23:00

This question has been asked before and already has an answer. If those answers do not fully address your question, please ask a new question.

  • You will be fine keeping it in the attic - I found heat sink made it worse in most cases for me... I cannot understand how it helps others? Remember the SoC is designed to dissipate heat without a heat sink. Do not keep it in direct sunlight and do not wedge it in a tight space either. It will run just fine in the hottest of hottest summers. – Piotr Kula Jan 10 '17 at 8:02
  • Sort of a duplicate. What I'm really wanting to know is, does the Pi 1 throttle back to attempt to reduce SOC temp like the Pi 3 does. – mabnz Jan 10 '17 at 22:26
1

The heat generated by the SoC is heavily dependent on the load. Note that idle Raspberry Pi 2/3 will perhaps not need any heat sink even at these temperatures, but will need it at any temperatures with full load. In my experience, when running SysBench (prime numbers) on all cores, the SoC without heat sink will heat up in one to two minutes to the maximum temperature (80 degrees C) , and will start throttling down heavily.

To maintain running the processor at full clock for such loads you need a heat sink, and it better be a big one. For our application we use aluminum plate (part of the case, about 200 cm^2 is the size of the plate), thermally connected to the SoC, and the whole plate gets quite warm to the touch, I would say something like 40C.

AFAIK this is the same behaviour than with Raspberry Pi 2, but it gets a bit less hot than Pi 3.

If you are not planning to run Raspberry at such heavy loads, then perhaps you do not need Pi 2 or Pi 3, take Pi 1 and you will be fine with small heat sink sold specifically for Raspberry Pi.

  • whats a BIG one? 2cm x 2cm or a car radiator? :) – Piotr Kula Jan 10 '17 at 8:04
  • Something you would ordinary put on a PC processor, just without fan. 5x5x3 cm should do, use thermal paste. You will also need some kind of thermal conduit, because such big heat sink will not fit to the board itself. So maybe solid aluminum bar (SocWxSocHx2 cm) as a conduit, then heat sink on top. 2x2cm would probably do with a fan, not without. Pi 3 is a very hungry animal. – xmp125a Jan 10 '17 at 9:23
  • Seriously ? That sounds a bit overkill.. but yea :) Does it look like this? raspberrypi-spy.co.uk/wp-content/uploads/2016/03/… :) – Piotr Kula Jan 10 '17 at 9:55
  • 1
    @ppumkin Seriously, yes. Well, that is an overkill, but in our lab we were unable to cool down Pi3 at full power with any heatsink that would fit the space above the SoC. Finally, we built U-shaped bridge (U shaped due to some space constraints immediately above the SoC), attached to aforementioned aluminum plate. It makes for a nice hand warmer now, so it is certainly 40C+ – xmp125a Jan 10 '17 at 12:50
  • Wow.. Seems like you guys really have a legitimate reason for putting a heat sink on there. :) Do you run something on it that clocks the CPU 100% for 24/7 ? Deep learning code or something awesome like that. – Piotr Kula Jan 10 '17 at 13:09

Not the answer you're looking for? Browse other questions tagged or ask your own question.