Noise reduction: 12V to 7V fan adapters

[Foppy]

I have seen a few people asking about how to reduce the noise levels of their case fans, and happened across a product which lowers the voltage supplied to fans. I'm wondering if anyone's had experience with these, or if they're any good. They claim to reduce noise by 40% - but I'm sure that comes at the price of a 40% air flow reduction. Perhaps a good solution for some of those louder 120mm fans which have CFMs in the 90+ range?
I'll post a URL to what I'm talking about if necessary - I'm not sure if that'd be considered advertising, since it is a link to a product on a separate retailer's website.

[Paul -The Mad Hatter]

it sure cuts out the the noise, but like you said, it comes at the cost of performance.

*600th post* ;D

[popadel]

If you cut the fan rpm with a resistor or a transistor, you could damage the fan. Ensure the fans voltage range is maintained, and try to cut current only not volts.

ENGENEERING TIP FOR THE DAY

[Foppy]

Originally posted by popadel
If you cut the fan rpm with a resistor or a transistor, you could damage the fan. Ensure the fans voltage range is maintained, and try to cut current only not volts.

ENGENEERING TIP FOR THE DAY

It's the kind of thing which runs both the 12 and 5V lines into one another - not sure if that's what you mean by current instead of voltage (still a bit behind on basic engineering)

[It_The_Cow]

It would probably better to just do it yourself. If I'm interpreting what you're saying correctly, it basically changes the ground to the +5 lead. It would be easier to just do this yourself.

As for the current/voltage thing, he means reduce the amps going into your fan to make it rotate slower. Most fans have a very very tolerable voltage range (~7 to 12+) so lowering the amount od volts won't damage it unless it's specified somewhere.

It also wouldn't result in a 40% airflow restriction. There's probably some formula for finding exactly how much you will lose, but I don't know it... yet. It most certainly won't be equal to the percent of power you take away, though. It may, but it's doubtful