Using Old CPU fan for case fan.

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Carlosthehuman

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Sep 24, 2016
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i took out a fan from the CPU of an old dell optiplex computer.
on the back it says 12V= DC 1.30A
i have tried using for it for my new pc but it will not turn on.
it is a four pin. its definitely not dead because i plugged it back into the old motherboard and instantly starting spinning.
i saw a post saying it wasnt receiving enough voltage. But found no clear way to up the voltage for the fan?
ASUSTeK Computer INC. Rampage III GENE
that is my motherboard.
 
Solution
Karadjgne
Most fan headers modern boards only support upto a supposed 1.0A. Reality is that's pushing your luck, don't count on anything more than 0.7A at most. You are asking for the mobo to supply 1.3A. That's not going to happen and it could cause damage trying. It's a Dell. If you consider it proprietary, you'd not be far wrong. The only way on a modern system to get that fan to run is adapter it to a molex supply using the header for tach/pwm wiring only.

4 pin is pwm. That's a constant 12v source, ground, tach and pwm signal. The fan needs only 12v from anywhere. The tach reads the speed and the signal wire turns the fan on/off in a 'pulse' to modulate speed. So a specific molex adapter is needed that'll pull 12v @ 1.3A from the power...
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Karadjgne

Karadjgne

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Most fan headers modern boards only support upto a supposed 1.0A. Reality is that's pushing your luck, don't count on anything more than 0.7A at most. You are asking for the mobo to supply 1.3A. That's not going to happen and it could cause damage trying. It's a Dell. If you consider it proprietary, you'd not be far wrong. The only way on a modern system to get that fan to run is adapter it to a molex supply using the header for tach/pwm wiring only.

4 pin is pwm. That's a constant 12v source, ground, tach and pwm signal. The fan needs only 12v from anywhere. The tach reads the speed and the signal wire turns the fan on/off in a 'pulse' to modulate speed. So a specific molex adapter is needed that'll pull 12v @ 1.3A from the power supply, but the split on the adapter goes to the motherboard header for the signal wiring. These adapters run @ $7. So does a new fan.
 
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Solution
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Carlosthehuman

Commendable
Sep 24, 2016
29
0
1,530

ah okay. i search endlessly around the internet for an answer. kind of anti climactic. |
thank you
 
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C

Carlosthehuman

Commendable
Sep 24, 2016
29
0
1,530

ah okay. i search endlessly around the internet for an answer. kind of anti climactic. |
thank you
 
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