Subject: Case Fans
By: Yeaggerman (IP: 66.233.3.*)
Written on: 29-08-2006 21:32

I just recently built a new computer. I have two 120 mm and one 90mm case fans. The two 120mm fans won't start running on their own when I startup the computer after shutting down. The 90mm fan will start on it's own but not the two 120mm. I can push the two 120mm fans with my finger and make them start and they will run fine after that. How can I get them to start on their own also?

By: Ray (IP: 84.65.117.*)
Written on: 03-10-2006 04:03

If a 12v 120mm fan (or any fan for that matter) only starts from stall speed with a prod the fan is getting some juice but not enough to overcome initial inertia OR is getting the full 12V but has dried-out/worn bearings. A fan really only needs minimum juice to keep spinning (in a normal environment) and a dry/worn-out bearing would sound LOUD!

I can mimic insufficient juice with my testbench PC - I have two 120mm 12v 0.28A fans spliced into the main 12v PSU supply via a variable POTentiometer. When the POT is set to
By: Ray (IP: 84.65.117.*)
Written on: 03-10-2006 04:08

... "minimum" (approx 5V) the fans run won't start. If I prod them they will start.

Check the voltage to these problem fans. If they are at 12V, oil the bearings.

HTH, Ray
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