Genuine Dell Power Supply 305W for Dell OptiPlex GX320 and GX620, and Dimension 3100, E310, E510, and 5100. All of our power supplies are pulled from new cases, fully tested, and guaranteed. We guarantee our products will work for you, however, before ordering, please check your existing power supply to ensure this replacement is the most appropriate for your system. Please check the power supply model number, the number and type of connectors, the voltage tag, and any other relative features. If you have any questions about the compatibility of your system, please do not hesitate to contact us! Connectors: P1 - 24-pin ATX Motherboard Power, P2 - 4-pin P4 motherboard power, P3 - 4-pin SATA standard power connector, P4 - 6-pin Dell proprietary connector, P5 - 4-pin SATA standard power connector P7 - 4-pin floppy connector, P8 - 4-pin Molex Power Connector, P9 - 4-pin Molex Power Connector. Buyer will receive MC164 or similar. If you request another model, please inquire before purchase.