HP dx7400 - Microtower PC Troubleshooting Guide

System does not power on and the LEDs on the front of the computer are not flashing.
Cause Solution
5. If the 5V_aux light on the system board is off, then replace
the power supply.
6. Replace the system board.
Table 2-1 Solving General Problems (continued)
ENWW Solving General Problems 13

HP dx7400 - Microtower PC Specifications

General

Memory	Up to 8 GB DDR2 SDRAM
Audio	Integrated High Definition Audio
Power Supply	300W
Processor	Intel Core 2 Duo, Pentium Dual-Core, or Celeron
Storage	SATA Hard Drive
Optical Drive	DVD-ROM, DVD+/-RW
Graphics	Integrated Intel Graphics Media Accelerator 3100
Networking	Integrated Gigabit Ethernet
Expansion Slots	1 PCI Express x16
Ports	1 serial, 1 parallel, audio in/out
Operating System	Windows XP Professional