PWM Fan in Sawtooth G4?

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PWM Fan in Sawtooth G4?

Hola!

I'm new to the support communities, but have visited here often and have gleaned tons of great information over the years. Thanks for sharing all the great knowledge! I'm hoping someone may have insight into the possibility of using a PWM case fan in a Sawtooth G4. Japamac's website was very helpful in determing appropriate power supply and fan replacements, but I'm confused when in comes to fan connectors, variable speed fans, fan controllers, etc. The original fan I would like to replace has a small green "sensor" on it that I believe regulates the fan speed. Can a PWM fan be used for this same purpose? From what I've read, a PWM fan requires a connection on the logic board, which I don't think the Sawtooth has. Are new fans being made that have the green "sensor" like the original? My hope is to find a new fan that will speed up / slow down automatically. Thanks in advance for any advice!

Mac OS X (10.5.8), 450 MHz Sawtooth G4

Posted on Nov 15, 2012 6:37 PM

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Answer 1

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japamac

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24,400 points

Nov 16, 2012 5:31 AM in response to RogueArtist

PWM fans need logic board connection and PWM aware boards to function in the true sense.

Voltage control by the logic board and OS kexts can be accomplished using two wires for a 12v connection method.

True PWM control is not possible without a special controller, but the fans can still function as a normal fan

If you are replacing a thermally controlled fan (small green sensor), another thermally controlled fan might be better.

In the PSU, other sensors allow the PSU to control voltage to the fans, so variable speed capable fans can be used (with or without thermal sensor).

Which fan are you wanting to replace?

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Answer 2

RogueArtist Author

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Nov 17, 2012 10:21 AM in response to japamac

Hi Japamac,

I'd like to replace the original case fan. It's a noisy sucker. I had a feeling a PWM fan wouldn't work, but it sounds like a new fan with a sensor would serve the same function. Should I search specifically for "thermally controlled fans"? Should I also be looking for something specific on the PSU side? I just replaced the original with a new ATX PSU and it works great, though I don't think it has any specific connectors for fans. Thanks for your help!

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Answer 3

Nov 17, 2012 11:46 PM in response to RogueArtist

If it helps, I had one of these in a G4 Digital Audio with many upgrades, and it worked well.

http://www.frozencpu.com/products/10352/fan-677/Akasa_120mm_x_25mm_Auto_Thermal_ Fan_-_800_-_2300_RPM_26C_-_45C_-_AK-174BKT-B.html?gclid=CK7JyamC2LMCFal7QgodBBkA Hw

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Answer 4

japamac

Level 7

24,400 points

Nov 18, 2012 1:47 AM in response to Dave Hamilton

Nice fan. Plenty of airflow, good pressure.

How's the noise compare?

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Answer 5

Nov 18, 2012 8:40 AM in response to japamac

It was about the same as the stock fan, which was running fine at the time. I just wanted more airflow.

The position of its heat sensor (clockwise) was important. It needed to match the stock fan. I had neglected to do that at first, and had to reinstall it.

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Answer 6

RogueArtist Author

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Nov 18, 2012 9:10 AM in response to Dave Hamilton

Thanks Dave!

I was actually searching last night and came across that same fan. Thanks also for the heads up on the sensor position! Thanks also Japamac for pointing me in the right direction - and a big thanks for all the great info on your website. Can't wait to (not) hear the difference!

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