HP Pro 4300 manual Some models, is set to the appropriate voltage. Proper

Power LED flashes Red four times, once every second, followed by a two second pause, and the computer beeps four times. (Beeps stop after fifth iteration but LEDs continue flashing.)

Cause	Solution
Power failure (power supply is overloaded).	1.	If equipped with a voltage selector, check that the
		voltage selector, located on the rear of the power supply
		(some models), is set to the appropriate voltage. Proper
		voltage setting depends on your region.
	2.	Open the access panel and ensure the power supply
		cable is seated into the connector on the system board.
	3.	Check if a device is causing the problem by removing
		ALL attached devices (such as hard drives or optical
		drives and expansion cards). Power on the system. If
		the system enters POST, then power off and replace
		one device at a time and repeat this procedure until
		failure occurs. Replace the device that is causing the
		failure. Continue adding devices one at a time to ensure
		all devices are functioning properly.
	4.	Replace the power supply.
	5.	Replace the system board.
The incorrect external power supply adapter is being used on	The power supply adapter must be at the correct power
the All-in One or USDT.	rating and use the Smart ID technology before the system
	will power up. Replace the power supply adapter with the
	HP-supplied power supply adapter.

Solving Power Problems 115