Hi

I have a 3 year old laptop which has suddenly developed the infamous
spontaneous abrupt shutdown syndrome. This is usually attributed to
overheating caused by dirty fans, but I am not convinced.

- I have tested various combinations of CPU speed settings, workloads,
power-management modes, AC vs batery, ambient temperature, etc.
- Shutdowns happen in the BIOS too, so it cannot be a software issue.
- I have enabled self-tests in the BIOS and used memtest86+.
- I have fully disassembled the laptop and reseated every connector.
- I have removed all non-essential modules and peripherals: bluetooth,
wifi, modem, keyboard, LCD panel (running on VGA with a USB keyboard).
- I have cleaned the copper air ducts and operated the laptop with
external fans blowing on all large chips.

Before I call it quits I want to try one more thing: reflow the PCBs.

The idea is not to melt everything, but only to reconnect any shaky pad
and destroy possible tin whiskers (this is an early lead-free design).

Recommendations regarding prerequisites, choice of air gun vs oven,
and safe temperature cycles for this particular purpose would be
appreciated (I have zero experience with reflow soldering).

AC