The 8-pin EPS12V power connector is designed to supply additional power to the CPU, which is particularly necessary for high-demand systems, such as servers or high-performance gaming and workstation computers. This is typically in addition to the main 24-pin ATX power connector. The 6-pin PCIe connector is designed for graphics cards, not for providing additional motherboard power. The 4-pin MOLEX connector is often used for older hard drives and peripherals, not for additional motherboard power. Lastly, the 20-pin ATX is an outdated main power connector for the motherboard and does not provide the additional power required for high-performance motherboards.