HP EliteBook 840 G7 randomly Shutting Off.

[Soul-Tech]

My HP EliteBook 840 G7 keeps turning off randomly.  Fan is running properly. Heat sink is well clean. processor paste already changed still facing same issue. no hanging issue but it suddenly shutting off some times after 2 minutes, 10 minutes, 25 minutes even some times it takes an hours like 2 or 3 to shut off automatically without any warnings or an error.

I'm pissed off because of this issue. help me to identify the issue . anyone who experienced such type of issue??????????????? 

[Jupitero]

Hello.

Your problem sounds like a broken motherboard or another internal accessory failing and causing a short circuit. Try taking out the internal battery and using only the power supply for power.

Another reason would be a thermal cutoff for the CPU. Monitored the CPU temperature status with. e.g. Core Temp. If the temperature is 90°C or higher, it could indicate overtemperature with e.g. heatsink not contacting the CPU optimally.

To exclude any software faults, try leaving the computer on BIOS setup screen or running the HP Diagnostics (by hitting F2 on computer boot) and run some tests for a few hours to trigger the shutdown. If the computer does not turn off after sufficient time then the problem likely is not in hardware. If the problem only exhibits in Windows, I would probably reinstall it.

Since you have already replaced the heatsink and feel proficient with further hardware disassembly, continue with the following steps. I recommend keeping the Maintenance and Service Guide as a handbook with the (dis)assembly process.

If the computer still keeps turning off I would take the system board out to an ESD mat with all wireless modules, SSD etc removed. Only connect a single RAM module, external keyboard/mouse/display and power it on and again let it stay on. Try with another power supply as well (if you have one).

If it still powers off, your system board is faulty, perhaps a solder joint defect or something else. Very hard to diagnose (or fix) without proper tools and magnifiers. The Maintenance and Service Guide has product numbers for all your laptop parts which can be ordered from https://parts.hp.com, thru a HP service partner or just from Amazon and the like.