Chosen Solution

After a continuous use of ~1.5 hrs its suddenly goes into sleep, wakes up, sleeps again and then finally shuts down. I am running on AC power without battery.

Is there any way to trouble shoot or identify the cause of the problem?

Check your computer settings. All computers shut off after a while, even when they’re on AC. You’ll find a setting regarding Sleep Mode and Shut Down where you can change if your computer should shut down/go into Sleep Mode in X hours/minutes or never. That usually fixes it, however if the computer goes into Sleep Mode while use it’s worrisome and the problem may be deeper.