most probably people die at 109 to 110 degree farenheit
so when we convert it to celsius we get 41.11 to 41.66
but i think theres always a range over which people die… different people die at different temperature but i think the above will suit your purpose
High fever prevents enzymes from working properly. Different tissues react in different ways to this. For example, epithelium and muscle can tolerate much higher temperatures for longer times than, say, the central nervous system.
So I guess one could say that very high fever kind of brain-kills you, though the actual cause of death can be something like a severe cramp or respiratory/circulatory failure due to impaired control by the nervous system.