Notebook laptop power suddenly turns off and on randomly


Oct 21, 2016
Hello, I have my notebook HP (dv7-4080us), in the last few months it started to suddenly turn off like a power failure, and after about 4 or 5 seconds off, it turns back on itself. That means, fans, hdds, all the laptop completely losing power and then restarting again.
No BSODs, no warnings, it just turn off and on again by itself.

Test i have made so far:
- Mem Test from BIOS: passed
- Smart Test for both HDDs from BIOS: passed
- No battery present, it doesn't work since years.
- Full complete dissasemble, blowed with canned air, and thermal compound replaced from CPU and GPU with Arctic MX-2
- Disconnected all USB devices
- Replaced Power Charger with another original power charger with same voltage, amperage and wattage
- Replaced CR2032 battery of the motherboard.
- Formatting the entire disk and upgrading to Windows 10 original ISO, leaving it without any software besides Windows, to discard software issues and power failed anyway.
- Pluging the computer in different plugs on different walls.
- It loses power while Idle, while gaming, while brosing the internet, while even not entering into windows 10 and standing on the user screen.

I don't know what else I may test.
This issue started several months ago. At first the failure occurred, several times while booting windows 7, like 3 o 4 times in a row, until the auto-chkdisk was executed, and after that it booted normally, lasted a few hours and then suddenly again the power went off.

One day, i entered Windows 7 in safe mode (basic mode pressing F8), and it worked without problem. Thats when i thought it wasn't the power charger. But anyway i replaced it, and it failed again.

What else may be generating the system to sudden reset itself?
If in safe mode, it didnt lose power, may the short be produced by a component or function that is not used in safe mode?
May the fault must be in the motherboard where it randomly sometime when calling any routine or circuit that generates a short and turns off?

Is there is any soft testing that allows to know what can be the failure or the last action, since in administrative tools when I search the Event Viewer, only appears the power failure.

Thanks in advance!