Undervolted 5v USB Fan

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Munchbot

Munchbot

Honorable
May 24, 2013
299
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Hello, everyone,

I recently found this on amazon:
http://www.amazon.com/Phobya-USB-3-Pin-Adatper-30cm/dp/B00A5TFJ34/ref=sr_1_1?ie=UTF8&qid=1387088726&sr=8-1&keywords=phobya+usb+to+3-pin+fan+adapter+30cm

Would this work with a standard fan? Would I burn a USB port because the fan would use too much electricity? The fan I'm planning to use is the back fan from a Corsair 500r, which is a pretty standard 120mm one. (Although I can't find the exact RPM/ power draw)

Also, what is the amount of power I could draw from a standard USB port?

Thanks in advance!
 
Solution
D
According to wikipedia, USB 2 max power is 2.5w, USB 3 is 4.5w. Depending on how your motherboard / case is set up, what other devices you are using etc. other devices may or may not be using some of the available power.

Typical 120mm fan power is around 5 watts @12volts, some much more, some a bit less. At 5volts (USB voltage) the same fan would use around 2.1watts. ([5watts / 12volts] x 5volts). Therefore, assuming the full power is available it should be OK to use.

The fan will run much slower at 5 volts though, and may not even start up under its own steam (might need a poke to start spinning).

I would recommend using a molex to fan adaptor if possible, take the power direct from the PSU and theres no extra drain on the mobo.
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djjag1

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Dec 16, 2013
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According to wikipedia, USB 2 max power is 2.5w, USB 3 is 4.5w. Depending on how your motherboard / case is set up, what other devices you are using etc. other devices may or may not be using some of the available power.

Typical 120mm fan power is around 5 watts @12volts, some much more, some a bit less. At 5volts (USB voltage) the same fan would use around 2.1watts. ([5watts / 12volts] x 5volts). Therefore, assuming the full power is available it should be OK to use.

The fan will run much slower at 5 volts though, and may not even start up under its own steam (might need a poke to start spinning).

I would recommend using a molex to fan adaptor if possible, take the power direct from the PSU and theres no extra drain on the mobo.
 
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Solution
Munchbot

Munchbot

Honorable
May 24, 2013
299
1
10,960


Thank you very much! I was actually planning on making a USB desk fan using an adapter and two fan grills. Thanks for the information!
 
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