StarTech.com 400 Watt ATX12V 2.01 Computer PC Power Supply with 20 & 24 Pin Connector ATX 400 ATX2POWER400 Heavy-duty transformer designed to support high performance systems with several drives Smart fan adjusts speed to provide quieter operation while maintaining optimum cooling ATX12V version 2.01 compliant EMI/RFI power filtration system provides low noise/ripple for super clean and stable power to all system components High flow fan provides efficient cooling for the system and the power supply High quality connectors provide minimal resistance and enhanced electric conductivity Industry's leading safety approval ratings Our power supplies are compatible with all leading processors including Pentium 4