Case fan came with molex connector, but it works without it ?

Motherboards have a varying number of fan connections. Some have one chassis fan and some have 3 or more chassis fan ports.

The MOLEX connectors are for the PCs with less chassis fan ports than chassis fans, so they can still use the fans somehow.

oh right

what I have done is plug the fan straight into the motherboard


this won't make any difference in performance than when it was connected to the motherboard via the molex ?

No difference in performance.

It is better to have the fans plugged into the motherboard pins because the motherboard will be able to read the sensor and fan speed and temp, etc.
When you use the molex connector, the motherboard won't see the fan.

Somebody please correct me if I am wrong on this but afaik the motherboard can only read/modulate fan speed from a 4 pin port and usually the only 4 pin port is CPU_FAN.

CHA_FAN chassis fan ports, in my experience, are usually 3 pin ports which means no fan speed modulation on these and no difference between these and a MOLEX.

I believe that you are correct on the 3-pin connectors Raiddinn.
But many of the newer case fans are 4 pin and have sensors.
Here is one that i found quickly....http://www.google.com/products/catalog?hl=en&q=4+pin+fa...