I've been trying to undervolt this laptop since I've had to send it in for a motherboard replacement after it fried due to heat damage. This happened while playing Witcher 3 for less than 3 hours,while using a cooling pad with fans at max and temps were still hitting 95C. I followed a variety of guides on how to undervolt my specific unit and temps have been improved greatly (max of 70C), without sacrificing significant performance and even extending battery life. 

At first I used Intel XTU, but have switched to throttlestop 3 weeks ago (my issue happens while using either). The guide I followed at the time instructed to lower the voltage offset for the i7-7700hq to between -100mv and -120mv. This worked great for about 3 weeks, until my unit started crashing after less than 10 minutes of booting up. Since then, I have tinkered with different levels, progressively going down to as low as -60mv, only to find that it still crashes at times.
 
I haven't been able to pin down what exactly it is about my undervolting that causes the crashes, since I have been setting the voltage offset well below what is recommended and it still crashes (around -60mv instead of -100mv). However, I have noticed that when it crashes, if I reboot my unit and don't change the undervolt settings, it will keep crashing. Going into throttlestop and changing the voltage offset slightly (say from -60mv to -65mv or -55mv) will cause the unit to run stable, even during extended stress testing and gaming. As soon as I put it into sleep or shut down and reopen it it will crash sometimes. I will add that when changing the voltage offset, it has run stable for significant changes as well (from -60mv to -100mv), but the timing of the crashes seems always random. It crashes when least expected, even during low intensity tasks like watching a downloaded movie from Netflix. 

The crashes happen both while the unit is plugged in or on battery. I've treated this unit with great care to avoid any damage caused by dropping or knocking it. I'm just surprised to see other people undervolting up to -150mv on the same processor and their systems running fine while mine doesn't seem to follow this trend at all. I should add that the crashes don't give any error message or blue screen, as they are complete freezes of the system. At least the only thing I can find is event viewer claiming the system shut down unexpectedly every time I perform a hard reset. 

 Could I have overseen something? Are there any more ways I could check how to assure my system will run stable? Is there anything else I can do to pin down the cause of these crashes? I'm quite frustrated because this is the only method that allowed my to take advantage of this laptop's performance without frying it during game sessions.