I am trying to understand, why and how this happens.

While playing with my friend + 3-4 AI sometimes around like 15-30-50 turns after or even in the middle game his game crashes. I load it we continue then in 2-3 turn crashes again.
But I have never had this crash problem. we both have decent good PC -s (list below) his windows 10 and Graphic Card Drives are up to date and game is on SSD

Mine is
------------
I5-9600k
16 RAM
RTX 2060
------------

my friends is
------------
i7-7700k
16 RAM
GTX 1080 TI
------------


So why mine is not crashing but his is? please help me I want to play with him but he doesn't want anymore because of frustrating crashes