Troubleshooting Random Crashes with Video Corruption.

Hi.

I have this Toshiba A215-S4767 for some time now. It is now crashing randomly, but frequently. Sometimes while idle, and sometimes working. Mostly when in windows, only a couple times before finishing loading windows.

I reinstalled the OS, windows 7 pro, no change.

I disassembled it, cleaned it, cleaned all cards, memory, wifi, modem. Cleaned fans and reapplied tim to all chips.

No change.

Checked for corrosion on any components, but none show visible signs of corrosion or failure.

I measured all voltages before and after crash. I noticed 1.8V goes to 0.7V after crash, but Im stuck there. PWM input is 18.9V(charger) looks fine.

Could you please advise what to check for next?

Thanks in advance.