COMPUTER FUNDAMENTALS

Detailed explanation-1: -A P1 24 pin or ATX 24 power connecter is the standard motherboard connector. The P1 24 pin is made of Molex 39-01-2240 connector. These connectors main use was to provide extra power to PCIe cards, and have more than one power wire. The four extra pins it has are lines for higher current capacity.

Detailed explanation-2: -Almost all of the new power supplies used today feature a 24-pin power connector to connect to a computer motherboard. However, some motherboards still feature a 20-pin ATX power connection. Thankfully, almost all 24-pin power connectors are designed so that four of the pins can be detached or moved out of the way.

Detailed explanation-3: -If your motherboard’s current requirements are low enough then it will work properly with only a 20 pin power cabled plugged in. But if the motherboard draws enough current, then you can overheat the 20 pins you’re using on the 24 pin connector.

Detailed explanation-4: -Technically, a 20-pin ATX connector can be plugged straight into a 24-pin motherboard socket, leaving male pins 11, 12, 23, and 24 unconnected. The four pins that you are leaving open are just redundant lines for higher current capability (see this guide to ATX connectors and pinouts).