My computer started having problems during start up. Now it has gotten worse because when I press the power button, nothing starts up, even the fan and all I hear is four long beeps in five intervals. I have tried using a different power suppy but it did no good, I still got the beeps. I have also disassembled everything and asssemled them back and also it did no good. What could be the problem and how can I resolve it?
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From the Troubleshooting manual for your HP model (from HP.com):
Red Power LED flashes four times, once every second, followed by a two second pause. Beeps stop after fifth iteration but LEDs continue until problem is solved.
Power failure (power supply is overloaded).
The incorrect external power supply adapter is being used on the USDT.
- Open the hood and ensure the 4 or 6-wire power supply cable is seated into the connector on the system board.
- Check if a device is causing the problem by removing ALL attached devices (such as hard, diskette, or optical drives, and expansion cards). Power on the system. If the system enters the 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.
From the sounds of it, there might be a problem with your CPU, but you might want to include a bit more detail if possible. The beeps that you are hearing are commonly referred to as Beep Code, which are typically heard during POST.
From the guides linked above:
Description: The CPU has generated an undetectable error
It might be a good idea to disassemble your computer and carefully remove the CPU heat sink and CPU itself. Examine the CPU thoroughly to ensure that no pins have been bent, or that any thermal paste as leaked onto the CPU connectors on your motherboard.
If you can't see anything visibly wrong, I would highly suggest following @Ramhound's advice and refer to your user manual for further instructions.