There is a switch near the power cord, see las picture.This listing is for a genuine Dell Precision T5610 685W Switching Power Supply, model D685EF-00 with DP/N 0YP00X. It boasts 80 Plus Gold certification, ensuring high efficiency and reliable power delivery for compatible Dell systems. The unit features a hot-swappable design, making it ideal for servers or workstations requiring easy maintenance and redundancy. It includes a single internal cooling fan for optimal thermal performance and a proprietary Dell connector for seamless integration. Please verify compatibility with your specific Dell system model before purchase. The power supply is in good condition, ready for installation.