Case Fan Options

[mjperk]

Hi All,
I have a Raspberry Pi 3 that I am turning into a gaming station using RetroPie. I am overclocking the Pi so it can run N64 and PSX games better. The case is very much sealed and I have already measured temps near or at a level I'm trying to stay under. I have heatsinks installed now and would like to put a case fan in so they will have a bigger impact. I know there is much debate on the effectiveness and need for overclocking, heatsinks, fans, etc. For the sake of this question and my desire to simply get help I'd like to please just avoid that debate, assume I am set on doing this, and focus on  the question at hand instead.

I connected a 40mm fan which is rated for 5V and somewhere around 100-200mA. To be specific, I connected it to a 5V power rail pin on the header. I should have done more reading first, because as you are probably aware the 5V pin gets power regardless of the Pi's on/off state and so the fan remains on unless I completely remove the USB power source altogether, which is what I'm try to avoid.

Since I also have a strong desire to get more traditional power button on/off functionality, the ATXRaspi suits my needs almost exactly, and I think/hope I can make the fan work with it. So to cut to the chase--
If I leave the fan connected to the 5V power rail pin on the Pi and hook up the ATXRaspi as intended, will said 5V power rail pin only get powered when the ATXRaspi is tells the Pi to turn on and the Pi itself is running? That is, when I shut the Pi down and the ATXRaspi turns the Pi itself off, will power to the rail be cut as well and thus the fan would stop spinning? If not, is there a location on the ATXRaspi itself that I could connect the fan to and that would safely support an additional 100-200mA draw from the fan?

[Felix]

The ATXRaspi has several output "+" pins, and a USB-A so you could power your Pi from the USB or through the GPIO then use another "+" to power your fan. Then both would come on at the same time. If there was a fan that's temperature controlled that would be even more ideal since it would come on only when the temps get high and not kick in at the same time the Pi does.

I haven't tried a Pi+fan setup myself. The fan is a inductive/reactive load which might cause some noise no the 5V output from the ATXRaspi, you might need to add some capacitance (100uf or 470uf perhaps to help stabilize that inrush at power up). The Pi is also variable/dynamic load especially at peak loads (startup for instance).
But 200mA average extra should not be a problem for the ATXRaspi.

[Felix]

Update: I got a 5v/0.2A fan to try out and there is no problem using it with the ATXRaspi. It comes on at the same time as the Pi comes on and it stays ON all the time as expected.