Asus x58 4-pin chassis fan

[cheyrn]

The manual says that only chassis fans 1 and 2 are controllable by the (spelling impaired) "fan xpert" and the BIOS also only has options to control the speed of fans 1 and 2. My case (antec three hundred) has fans with molex connectors. I've bought one fan with a 3-pin connector and replaced the rear fan with that. Do you know where I can get a fan or an adapter to connect a fan to the 4-pin chassis fan 1? All my searches have resulted in 4-pin meaning molex connector. If it's a fan I would want one that is quiet like.

The chassis fan 1 connector is a 4-pin connector:

+5V
Fan in
Power in
Ground

It has a plastic tab that prevents a floppy drive power adapter from fitting, for example. Do you know what this type of connector is called?

The other is a 3-pin connector:

Rotation
+12V
Ground

Also, I'm curious, if there was a reason to add more fans, is there a reason to connect them to the other 3-pin fan connectors that aren't controllable (as opposed to connecting them to the power supply via a molex connector)?

 

[clutchc]

4 pin headers use Pulse Width Modulation to control fan speed (4 pin). Some boards allow 3 pin fans to vary their speed also by varying the voltage to the DC fan motor. Also, remember, you can plug a 3 pin fan into a 4 pin header; it just won't have PWM control. You don't need an adapter.
3 pin fans use the 3rd wire for speed feedback.
If your case fans came with only a Molex connector, they probably are 2 wire fans. In that case, you won't have any speed feedback or speed control over the fans. But you can get adapters to mate them to the board's headers if you want. Or just connect them to any molex connector from the PSU.
If you want a 4 wire fan, search for PWM fans.
http://tech-reviews.co.uk/reviews/akasa-120mm-apache-fan/