Voltage question for Noctua 40mm fan \ VOGONS

Voltage question for Noctua 40mm fan

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First post, by GabrielKnight123

Posted on 2020-01-18, 12:41

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I bought a Noctua NF-A4x20 fan and it's 12 volts but the fan has 3 wires with black/red/yellow so ground, red (5 volts) and yellow (12 volts) but my molex to fan (12 volt) adapters only have ground and 12 volts and the pin arrangement for the adapter is putting the 12 volts to the red 5 volts wire on the fan. The fan is an FLX fan and not a PWM so should I modify the adapter to put 12 volts to the yellow wire on the fan or should the adapter also have red 5 volts to the fan or just 12 volts?

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Reply 1 of 3, by derSammler

Posted on 2020-01-18, 12:44

derSammler Offline

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Fans don't use more than one voltage.

Black is GND
Red is either +5V or +12V, depending on if it's a 5V or 12V fan
Yellow is revolution sensor

Reply 2 of 3, by GabrielKnight123

Posted on 2020-01-18, 13:15

GabrielKnight123 Offline

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derSammler wrote on 2020-01-18, 12:44:
Fans don't use more than one voltage. […]
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Fans don't use more than one voltage.

Black is GND
Red is either +5V or +12V, depending on if it's a 5V or 12V fan
Yellow is revolution sensor

Ah yes thank you just after making this post I remembered an old post I asked for a power supply fan here: Re: What is yellow wire on 3 pin fan

It's strange to me the 12 volt wire is red and the tachometre/revolution sensor is yellow

Reply 3 of 3, by kaputnik

Posted on 2020-01-18, 14:51

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GabrielKnight123 wrote on 2020-01-18, 13:15:

derSammler wrote on 2020-01-18, 12:44:
Fans don't use more than one voltage. […]
Show full quote

Fans don't use more than one voltage.

Black is GND
Red is either +5V or +12V, depending on if it's a 5V or 12V fan
Yellow is revolution sensor

Ah yes thank you just after making this post I remembered an old post I asked for a power supply fan here: Re: What is yellow wire on 3 pin fan

It's strange to me the 12 volt wire is red and the tachometre/revolution sensor is yellow

The Molex connectors are the strange ones. They carry two different VCCs, guess they picked different colors for them to signify that. The "standard" colors are red for VCC and black for GND otherwise.

One could of course argue that it would be less confusing if they'd picked any other color than yellow for the fan tacho signal though 😀

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