The final result: how I powered an AMD Wraith CPU cooler with an adjustable 12V DC power supply

9 months ago by durinn to c/hardware

I disassembled an AMD CPU Wraith Cooler, meaning, I took the fan off of the heatsink, because I want to attach the fan on top of a Raspberry Pi that I’m using as a router. The Pi runs quite hot because it transmits several hundred megabytes per second, non stop, and I want to give it some cooling. (It already has its own heatsinks on its various chips inside the chassi and I don’t want to use the little shitty Okdo fan, because it’s loud.) Is there any smart solution to how I could power this 4-pin fan? It needs 12V DC. [https://programming.dev/pictrs/image/0202a0da-5fa8-4399-9cc7-36ed80624687.jpeg] This is the Pi with its chassi. [https://programming.dev/pictrs/image/b346fa5e-05ca-4b88-9c24-fbb7128bfc46.jpeg] And I’m considering something barbaric like this. [https://programming.dev/pictrs/image/84163d72-a763-4eb0-8071-e178ac518b1d.jpeg] Are there perhaps conveniently positioned GPIO pins on the Pi that the 4-pin connector could just slide on to and just work? Never mind this. The Pi 4 that I’m using can only output 5V: [https://programming.dev/pictrs/image/2e479ba3-b8a7-4cac-ac14-618bdd94ea71.jpeg] Or would I need to cut off the 4-pin connector to expose the individual wires and attach them to a 12V DC adapter? Or any other genuis solutions? :)

Follow the link for background info!

Thank you so much for all the great advice! What a nice community! :)

I pushed out the pins from the 4-pin connector using a SIM tool:

I bought a 12V DC power supply with adjustable voltage (3~12) so that I can adjust the fan speed to my liking (noise, temps). The power supply came with a bipolar terminal. How in the world could I be this lucky. No need to carve any wires here (although it would have been nice to finally learn how to do that too...):

I put back the sense and control pins into the connector in order to avoid accidental shorts and what not. I have no idea why ground goes into the negative node, but it was the only plausible configuration, since the power simply has to come from the positive node, according to conventional current:

And voila! I have no idea why I'm unable to upload the GIF of my fan spinning, so you'll have to take my word for it.

Thanks again!

ferric_carcinization 3 points 9 months ago

I have no idea why ground goes into the negative node, but it was the only plausible configuration, since the power simply has to come from the positive node, according to conventional current

Electronics are complicated. Ground = negative node in most circuits. Unless you have studied electronics explicitly, most prior explanations you have heard are just good enough approximatons for whatever thing it was about.

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emotional_soup_88 3 points 9 months ago

Thanks! Yeah, I'll leave it at that now and just enjoy that it works. I've recently been studying the very basics just out of curiosity, but when they started to talk about earth being a giant sink for electrons, they lost me (for now). I'll definitely pick it up again next month. 😊

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