So basically what i did so far i replaced my old case fan with one of these however my mobo has a 4pin fan header and the corsair fan has only 3 pin it did go in obviously and works just fine.
i bough a 4pin to 3pin cable : http://www.quietpc.com/zm-mc1
I added my new fan but the new cable only had 2 pin that i could use however even tho the fan had 3 i still could make it work.
i wrap it up all good fans works just fine but the problem is led don't work on either of em and im wondering if there is something i did wrong because im kinda confused now with all the 2-3-4 pin bullshit any help would be great.
-Basic 4 pin molex fans just use 2 of the 4 pins(Black and Yellow[12 volt]) from the power supply.
-3 pin fans use all 3 pins, but only 2 of them power the fan(black and red most times). The third pin is to allow a board to see the speed. 3 pin fans can be speed controlled by changing the voltage(on the red wire).
-4 pin PWM fans get power from the same wires as a normal 3 pin fan and also send speed information back on the 3rd pin the exact same way. The 4th pin on a PWM sends a pulsing signal that the fan uses to control its speed. These are more efficient and can in many cases run slower and start slower than 3 pin fans.
Please note that 3 pin fans can be connected to 4 pin headers without any issues(you will loose speed control so the fan runs full out). The extra pin will just sit beside the connector. They plugs are normally keyed to only allow them to fit the right way. PWM fans can also be connected to a 3 pin header leaving the extra section of the plug hanging over the edge(if the port uses voltage control the fan speed will still work).
The only reason I can see your LED's not working would be either a defect or running the fans on too low of a voltage. Please check the connection.