Green LED on back indicates power, Turns off immediately when hitting power Button
Product: HP Envy Desktop 750-537cb
13 months old and when we hit power button nothing happens except green power light on back goes out. We have to unplug power cord in order to get green light on again. Power supply tested OK but replaced it anyway, disconnected and reinstalled cables and ram but still have the same problem.
You have a system short if the power supply is shutting down and unplugging the PC resets the power to the system. It is probable the original power supply is okay if you replaced and have the same problem.
Reduce the PC to a minimum config (RAM, CPU), this means disconnect all other components (Front USB, HDD, DVD, front USB card reader), then check for power and POST after disconnecting one component at a time.
The motherboard could also be shorting out which causes the power supply to shut down.
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