[SOLVED] Which side to connect a 2-pin male Molex to a 4-pin female?

[datnguyen210801]

I have a 12V 1.6A case fan with 4-pin connector and my motherboard has no slot for it. Therefore I use an intermediate cable to convert so that I can plug my fan to the female Molex of my PSU but my male Molex only has 2 pins. My female Molex cable is all black so I don't know which side to connect. Does side matter? I want my fan to run at 12V full speed.

 

[velocityg4]

The connector should have a notch on each side. It only fits one way.

Notice how it rounds off a little on each side in the linked diagram.
https://raspberrypi.stackexchange.com/questions/40078/molex-to-micro-usb-to-power-pi

Edit: As far as a fan goes. There'll be a huge audible difference if you connect to the 12V or 5V side. If you managed to force it the wrong way.

 

[Paperdoc]

As velocityg4 says, there is only one way the connectors will fit together - no confusion. The adapter you got has only two pins becasue it connects only the 12 VDC lines to that fan. On the female Molex from the PSU, the Red and one Black lines are for 5 VDC, the Yellow and a Black are for 12 VDC. You will see that the adapter connects the Yellow and one Black to pins 1 and 2 of the fan's 4-pin connector.