I have one running next to a basement window that gets fairly cold. It barely gets down to 90F when 10F outside.
The one behind a dresser in the bedroom sits at 120-130F for the past month.
I haven’t left an RPI3 running with piware for long enough to get any stats(once piware worked I have been using it for testing stratux. no luck so far).
I google of “do rpis need heatsinks” reveals differing opinions.
One is that the heatsinks done’t work and actually insulate the CPU causing it to heat it.
(partially caused by crappy heatsinks and thermal compounds)
reddit.com/r/raspberry_pi/c … eat_sinks/
One comment from raspberrypi.org suggests maybe for an overclocked RPI3
raspberrypi.org/help/faqs/# … ceHeatsink
"3. DOES IT NEED A HEATSINK?
You should not need to use a heatsink, as the chip used in the Raspberry Pi is equivalent to that used in a mobile phone, and should not become hot enough to need any special cooling. However, depending on the case you are using and the overclocking settings, you might find a heatsink to be advantageous. We recommend the use of a heatsink if overclocking the Model 3B. Of course, if you just like the look of one, you will not hurt the Raspberry Pi by placing an appropriately-sized heatsink on it. -Performance and Cost Considerations -Top.
8. What is its operating temperature?
The Raspberry Pi is built from commercial chips which are qualified to different temperature ranges; the LAN9512 is specified by the manufacturers as being qualified from 0°C to 70°C, while the AP is qualified from -40°C to 85°C. You may well find that the board will work outside those temperatures, but we’re not qualifying the board itself to these extremes. -Performance and Cost Considerations -Top"