Genuine Dell NH429 / 0NH429 280-watt internal PFC power supply documented for configuration-specific Dimension C521 and OptiPlex 330, 740, 745, and 755 systems. Exact-number sources associate NH429 with H280P-01 / HP-Q2828F3P labels and a desktop-chassis layout. MH596, MH595, RT490, P9550, U9087, X9072, JK930, and wider fitment lists are substitution clues only. Power cord, mounting hardware, adapters, cables, and accessories are not assumed included. This inventory record explicitly identifies the condition as New. Match NH429 / 0NH429, full model/revision, service tag, exact chassis, 280-watt and PFC labels, dimensions, connectors, cables, pinout, and included items before ordering.