If you are refering to the 20 or 24 pin molex connector, this is the motherboard power distribution subsystem from the power supply.
If you are refering to the several other small connectors, they have various functions. Front panel indicators and switchs, USB distribution connectors, fans, CD audio, etc.
The LGA 1156 connector is also called the H or H1 socket. It connects the motherboard to the CPU, or central processing unit. Without this connection, the computer will not function.
A SATA power connector is what connects the SATA device to the PSU (power supply unit), therefore giving it a source of power. There is another cable that connects to the motherboard but that is just for data transfer.
How is PS2 connector on motherboard
There should be a large connector coming from the Power Supply unit. You may have a 20 pin or a 24 pin connector on your motherboard. Most power supplies come with a 20+4 pin connector which allows them to connect to both 20 and 24 pin mother bards.
the regular ATX has a 20 pin power connector, while the enhanced ATX power connector has 24 pin power connector.
20- pin connector
PGA
ambot
The serial ATA connector on the motherboard.
The panel involves a motherboard that is connected by pins to the FP connector. The motherboard uses a standard FP connector, therefore, easy to figure out.
The motherboard form factor AT only has the 5-pin AT keyboard connector built in.
20 pin P1 connector.