Laptop Shuts down abruptly under load

Question

TL:DR

7 year old laptop, new thermal paste, recently cleaned fan, disconnected battery, suddenly powering off under load.

Specs:

Lenovo Flex 2 - 15 inch variant

i5 4210U

GeForce 840M

240 GB SSD

1 TB HDD (replaced Disk Drive with HDD Caddy)

12 GB RAM (4 originally, added 8)

Solutions Tried:

New Thermal Paste

Cleaned Fans

Disconnected and reconnected battery

Set everything to use Integrated GPU rather than the 840M

Long Version:

My modified laptop is around 5/6/7 years old. I love it. It survived everything I threw at it. Games? Handles it like it you’d expect. A tad over 60FPS no more than 80FPS (conditional). Editing? Handles 60FPS 1080P.. with restrictions. This afternoon it started powering off suddenly whenever I load up games. I’ve disconnected it’s battery, changed it’s thermal paste and cleaned out it fan. Nothing worked. Any Ideas? Is it time to say farewell to my old friend?

Answer 1

Replace the battery.
Your power supply's job is not to power the computer, it's to charge the battery.

The battery is responsible for providing 'surge' power when the computer needs it. It is designed to cope with this task.

The power supply's job is to provide trickle-charge power to the battery.

If the battery is failing or removed, then every time the computer requests more power, the power supply can't keep pace & the computer will crash hard.