Ground pin on connectors?

I was reading somewhere about the marking on connectors (Molex I think, like the front panel connectors to the main board). There is a triangle impression on one of the pins. Is this a ground pin? I wish computer wiring had used a standard color coding. I know that on some connections, fitting them backwards does no harm but how about the pwr sw type?

The orientation of the power switch connector is of no importance, the motherboard detects the short between the pins (I assume you don't have some ancient AT motherboard/case).

Computer wiring is rather standard.. The black wire is the ground, red or yellow live. Red usually +5V, yellow +12.