Note: Pay attention to the strength of the individual outputs of your power supply (usually this information can be found on the power supply) and the power requirement of all of the components in your PC used.
This 8-pin power extension cable is needed on modern EPS, ATX and BTX mainboards for supplying power to the processor. In contrast to the older, 4-pin ATX12V Mainboard- and power supply connections, this connection has double the width, 2x 4-pin. The connector can be split into two 4-pin connectors on the mainboard side, from which one of them also fits the older mainboards. Even only a 4-pin connector can be inserted onto the other 8-pin side individually, the other 4 pins then do not receive any current. Please read the instructions provided by the mainboard manufacturer.