Asus ROG 750jm random power off? What could it be?

[Opaque49]

Asus Rog Laptop that I’ve research quite a bit. I don’t know if it’s overheating within minutes, a fan malfunctioning or other hardware failure but this power off has no blue screen instantly kills the power to the computer and upon restarts it barely wants to sometimes I may link a video.

What my issus/problem I turn on the laptop. sometimes the computer starts goes to the windows screen then shuts off immediately like a flick of the switch. Then sometimes it doesn’t even make it that far where I could just turn it on and the laptop will just completely turn off a few seconds or even a second after starting it up. Everything turns on display wise can go to bios it seems to not restart if I’m in bios at least I can’t recall it doing it there if I have made it that far...

Recently after the initial start windows loading icon it still can go into bios fine or windows restore but tried that and it always restarts in the middle of a restore. Which I think caused this issue with it stopping from going into the windows screen or pulling up past the short loading screen. It shows a blank page with the pointer icon. Again if I have even made it that far without it already turning off. It doesn’t reboot it turns completely off fans stop spinning everything shuts off as if I held the power button down.

I’m at a loss on what to do if anyone can help me. The laptop battery doesn’t work so it stays plugged in directly with the cable and has been like that for years with no issues. Also I installed a sad years ago and it’s always worked fine after install.

Thanks for anyone that can help me resolve this issue I’ll give you as much detail as I possibly can.

 

[helpstar]

Maybe the charger is defective or the power plug/ connection is flimsy.

Check your HDD with the HDD manufacturer´s tool on a bootable CD or USB flash drive, your RAM like this as well with memtest.org (USB autoinstaller)

Check temperature in BIOS

 

[Opaque49]

So started to pull the laptop Asus G750JM apart. Completely dismantled in a static free room. Checked over both fans seemed to be clogged with dust etc I cleaned both very well. Cleaned majority if not all of the board of lint dust etc. The next step was to replace all of the thermal grease on cpu and found which was done. Following that checked over the board for any outstanding looking damage or burns. I couldn’t find any or am unaware of the method of seeing which would be burnt of damaged. Well following this I completed the reassembly. I then turn on the laptop it runs fine for over 45mins to an hour could have been longer then shuts off like it previously has done. Then on restart pressing the power button it intially lights up for a split second then shuts off once again. Only way to make this process move forward is I noticed. Was to first remove the charging cable hold the power button for 30seconds discharging all electricity. This possibly made the computer turn on for a few minutes then shut off again to the previous process until power pulled. I then pulled both hard drives tested them in another computer worked flawlessly. Then tested each stick of ram seemed to also work fine. I was at a loss so I contacted a local but cheap computer repair shop to just diagnose my issue and he told me he tested the power cord and power box whatever Asus has with his and it still had the same issues. His result was motherboard failure but no description so made me very skeptical. Looking for help. I know this computer is salvageable just don’t know how to fix it properly.

 

[helpstar]

battery or the charge part of the motherboard