Still sounds like a cooling fan issue. I have also seen in computers where the heatsinks can become dismounted from GPU and CPU's or the thermal take dries up and cause the temperature to climb Very Fast, sometimes catastrophic with a nice crackle and smell. Does your system give off any odors when it freaks out? Is it warm to the to the touch anywhere that is an unusual amount of heat? Do you hear any fans running at all during operation? If no fans running, you might have one that is lockedup, bearings bad or some obstruction. ALSO...Some of these Fans will make Ticking noises if locked up, since they are a brushless motor induction fan that converts solid DC on a smal breadboard circuit into a Pulse Width Modulated signal to control the RPM's of the cooling fan.
I'd locate your cooling fans in the laptop, and find replacements at
www.mouser.com or try to find a replacement through the MFR, which will have a markup. If you know how to match up + and -, and match up the fan size, CFM's, and type, you can save yourself probably $20 to $40 per fan by buying teh fans through Mouser.