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Pi 3 CPU Fan

Posted: Sat May 14, 2016 1:39 pm
by Kratos
Hey everyone! I am looking for a small fan, one that fits directly on top a heat sink for the Pi 3 CPU. I plan on powering it by the GPIO pins. I am not too concerned about noise, but I do want the fan to be small enough to just fit on the heat sink. Any recommendations? Concerns? Links? Thanks!

Kratos

Re: Pi 3 CPU Fan

Posted: Sat May 14, 2016 3:34 pm
by Rive
Kratos wrote:Hey everyone! I am looking for a small fan, one that fits directly on top a heat sink for the Pi 3 CPU. I plan on powering it by the GPIO pins. I am not too concerned about noise, but I do want the fan to be small enough to just fit on the heat sink. Any recommendations? Concerns? Links? Thanks!

Kratos

Depends on heatsink size. I am running a $6 12v desktop fan (70mm x10mm) on my gpio 5v rail (pins 4 and 6). If you are using one of those small tiny heatsinks (two on lift in first pic), a little fan on it will be near useless, and you will be lucky to shave 5C off your temps in a case.

You only need a heatsink on the SoC, Dont fall for the "you need 3 heatsinks BS".

Most of us that have went with heatsinks and fans, realized quickly that the larger the heatsink the better.

For cooling, thermal testing/benchmarking, see;
viewtopic.php?p=952371#p952371

for ex:
Image
Image
Image

Re: Pi 3 CPU Fan

Posted: Wed May 18, 2016 2:45 pm
by Kratos
Thanks for the detailed post you put together in that link. I shall be exploring my options...

Kratos

Re: Pi 3 CPU Fan

Posted: Wed May 18, 2016 4:25 pm
by MarkHaysHarris777
I'm going to use this fan from amazom

I have a 30mm hole cut in the top of my clear case from Element14, and plan to mount the 40mm 5v fan in the top of the case above the heatsink on rubber fan mounts (very quiet, good airflow).

This fan is only 120ma and moves about 5.75CFM.

Re: Pi 3 CPU Fan

Posted: Wed May 18, 2016 7:53 pm
by Kratos
MarkHaysHarris777 wrote:I'm going to use this fan from amazom

I have a 30mm hole cut in the top of my clear case from Element14, and plan to mount the 40mm 5v fan in the top of the case above the heatsink on rubber fan mounts (very quiet, good airflow).

This fan is only 120ma and moves about 5.75CFM.
Thanks for the recommendation!

Kratos

Re: Pi 3 CPU Fan

Posted: Wed May 18, 2016 9:12 pm
by greenbag
If you live in the city, ie: not stuck out in the boonies somewhere, then open the yellow pages or google for electronic component shops in your area. You should be able to get a 25mm x 10mm fan for less than $10.

Re: Pi 3 CPU Fan

Posted: Thu May 19, 2016 8:09 am
by emptybee
I bought this set: http://amzn.to/1WDOKsB

Needs a bit of dremeling to fit properly around the micro usb and 3.5mm jack connectors. Also a bit of a pain to remove the SD card unless you remove some material from there. I soldered an inline 15ohm resistor to the fan to slow it down a bit (was quite noisy otherwise).

If you already have a case it's probably best to DIY a fan from a electronics store rather than pay for this kit but I like that it had everything I needed. Just a bit of bodge work to perfect it.

Re: Pi 3 CPU Fan

Posted: Thu Oct 26, 2017 9:46 am
by Alex_83
I have a very small raspberry CPU fan as those found on ebay. In few months it became very noisy. I pulled off the sticker on the fan and put a little thick oil for lubrication in the axis, powered it while the oil was going deeper due to gravity (and put the sticker back)and it is working now as new without noise for about 10 months. I've tried it with anti-rust oils like WD-40 before but because these oils are not so thick and evaporate, my fan started making noise in a few weeks again.

Re: Pi 3 CPU Fan

Posted: Thu Oct 26, 2017 1:05 pm
by HawaiianPi
For awhile I just used one of those USB port fans. The kind on a gooseneck flexible shaft. I plugged it into my Pi3 and bent it so it was pointing back and down, and even though my Pi3 was in a case enough air got through the various holes to keep it nice and cool.

Re: Pi 3 CPU Fan

Posted: Thu Oct 26, 2017 1:36 pm
by RaTTuS
Alex_83 wrote:
Thu Oct 26, 2017 9:46 am
I have a very small raspberry CPU fan as those found on ebay. In few months it became very noisy. I pulled off the sticker on the fan and put a little thick oil for lubrication in the axis, powered it while the oil was going deeper due to gravity (and put the sticker back)and it is working now as new without noise for about 10 months. I've tried it with anti-rust oils like WD-40 before but because these oils are not so thick and evaporate, my fan started making noise in a few weeks again.
wd-40 is not a oil / lubricant it is a water displacement fluid....
best best is to use a flirc case like
https://community.zymbit.com/t/encrypt- ... rry-pi/150
or
https://www.aliexpress.com/item/New-Ras ... 05786.html

others are available

Re: Pi 3 CPU Fan

Posted: Thu Oct 26, 2017 4:42 pm
by Burngate
RaTTuS wrote:
Thu Oct 26, 2017 1:36 pm
wd-40 is not a oil / lubricant it is a water displacement fluid....
According to Wikipedia (which, like me, is never wrong)
The long-term active ingredient is a non-volatile viscous oil which remains on the surface to which it is applied, giving lubrication and protection from moisture
According to WD40.com
wd-40.png
wd-40.png (34.51 KiB) Viewed 3953 times

Re: Pi 3 CPU Fan

Posted: Fri Oct 27, 2017 6:59 am
by RaTTuS
:) well , yes it's an oil and it can lube :D , but for things like fans it will not be good as the high viscosity will attract fluff and make it worse in the end .....
but noted ;)

Re: Pi 3 CPU Fan

Posted: Fri Oct 27, 2017 10:54 pm
by HawaiianPi
Here's a solution I just came up with last night.

My Pi3 is in a JBtek open sided case which had the fan on top.

Image

That fan was too loud, so I went digging through my box of spare parts and found a very thin 40mm fan, and instead of mounting it on top of the case, I used a small brass spacer on one corner and mounted it between the SSD drive and SoC heatsink.

Side view:
Image

Back view showing the spacer (corner of the Pi board by the red LED):
Image

With the original fan my temps topped out at 74C when maxing out the CPU. That's pretty warm, but still below the 80C throttling temperature. However, after switching to the thin fan mounted between the SSD and SoC heatsink my temps have dropped to a max of 55C (-19C).

If you don't have anything mounted over the top of your Pi you could do something similar with a larger fan.

Re: Pi 3 CPU Fan

Posted: Fri Oct 27, 2017 11:38 pm
by HawaiianPi
Expanding on my idea above a bit further, I dug into the spare parts box again and tried a few other fans. It turns out the spacing of the mounting holes on the Pi2/3 is nearly perfect for a 60mm fan. A quick test with some brass spacers on my Pi2.

.
OP_RPi_CPU_fan_2.jpg
OP_RPi_CPU_fan_2.jpg (75.33 KiB) Viewed 3784 times
OP_RPi_CPU_fan_1.jpg
OP_RPi_CPU_fan_1.jpg (85.87 KiB) Viewed 3784 times
.

And as an added bonus, it's now also a drone (WHOOSH!). Hard to control, though.

EDIT:
The Double-Tap! :lol:
.
RPi_Double_Tap.jpg
RPi_Double_Tap.jpg (77.74 KiB) Viewed 3761 times

Re: Pi 3 CPU Fan

Posted: Sat Oct 28, 2017 2:30 am
by HawaiianPi
Okay, all silliness aside. This is a 25x10mm fan on a heatsink I cut down from a larger one.
RPi_small_HSF.jpg
RPi_small_HSF.jpg (61.57 KiB) Viewed 3760 times
This is the info on the fan. I don't recall where I got it (probably ebay).
small_fan.jpg
small_fan.jpg (52.23 KiB) Viewed 3760 times
If your Pi3 is in a case, you could cut a hole in the case over the SoC heatsink and mount the fan on the case. That would allow for a wider selection of fans, because these tiny fans move almost no air.

Re: Pi 3 CPU Fan

Posted: Sat Oct 28, 2017 9:52 am
by gkreidl
Get a Flirc case and you don't need a fan.

Re: Pi 3 CPU Fan

Posted: Sat Oct 28, 2017 9:04 pm
by HawaiianPi
I just found some 60mm 5V fans on Amazon, so this,
Image
might not be as far fetched as I thought it was. :ugeek:

Actually most 12V fans work at 5V as well (just at a lower speed/CFM).