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I have a Pi3 in a fairly enclosed environment, and I found that, even when my Pi was relatively idle (5% CPU usage) the CPU temp was averaging around 80C, which is close to the 85C where the Pi starts to underclock and the 90C where the Pi starts to get damaged. Since I'm planning some more processor-hungry tasks, I want beef up the cooling, if only for performance reasons.

I already have a heatsink on the Pi's main chip, so I'm considering adding a very small fan. I found that even slightly blowing on the chip immediately takes the temp down to 60, so it's entirely an air-flow problem, so even a very weak tiny fan should work.

Unfortunately, I don't have any more room to add a power regulator to supply the fan, so I need to power it directly from the Pi's 5V power rail and controlled via a GPIO pin. What are the fan specs I should be looking for so it doesn't exceed the Pi's max current? Is anyone aware of any very tiny and silent 3.3V or 5V fans suitable for this?

Cerin
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You can power a small 5v fan off the 5V and the GND pins on Raspberry's GPIO pins. Check the GPIO layout HERE.

I use this Kit and use pin 2 and 6.

Hope this helps

DCL
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I can confirm that I also haven't had any problem powering a low profile 5V Noctua 40mm x 10mm fan from the 5V and GND pins. These pins are always on. This is on a Raspberry Pi 3B+ used as an Octoprint server.

The power drain is minimal.

Rob Willett
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You can not power a fan from the Pi's GPIO. The GPIO are all 3V3 and only supply a few tens of milliamps at best (you are recommended to draw no more than 16mA from an individual GPIO).

You can power a fan from a 5V power rail pin on the expansion header. You might be able to power a fan from a 3V3 power rail pin on the expansion header but that will depend on your Pi model. Early Pis had very limited 3V3 power available.

joan
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If you want a really silent fan, I suggest powering a regular fan with a lower voltage. The safest bet is to get a 5V fan and try it with 3.3V: it will almost certainly rotate at roughly half the RPM, which reduces the noise a lot. If it doesn't work, or the airflow is not sufficient, you can still power it with 5V.

Another option (that I personally use) is to get a 12V fan and power it with 5V.

There are some cooling assemblies for grahpic cards available on e-bay which include a small heatsink and a 5 or 12V fan. Some of those are really cheap and also quite small, so they fit the Pi perfectly. The screws/clips will not fit of course, but you can attach them with a very thin layer of super glue.

Dmitry Grigoryev
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