After upgrading to High Sierra (I have clean installed it), my mac (Macbook Pro 2010) needs unreasonably longer time to login. As a result, I have noticed that the temperature increases to around 100 C during the startup time (I have checked this right after login through Istat Menus). Meanwhile the fans are at 2000 rps. Apparently , the reason why fans do not speed up is because the system as a whole is within the safe temp with the only exception of the CPU temperature as CPU is busy processing all those startup processes. So the fans assume everything is alright and do not speed up.
Now my question is if this causes any harm to CPU as I think I read somewhere that quick fluctuations within a short range in the temp of CPU can cause damage to the CPU. I just wanted to know your ideas on this.
Best Answer
In iStat Menus, check the figure for 'relative to ProcHot' - so long as this is a positive value, all is OK in theory, though I would have expected the fans to ramp before that temperature was reached.
Maybe try resetting the NVRAM & SMC - Really confused about how to reset SMC and PRAM and NVRAM on my Macs and iPad and iPhone? has a comprehensive answer on how to do this for all Mac models.
Picture of where is shows on my machine, but as it's a dual processor Mac Pro no doubt it will look very different. [bottom half menu cropped off, to save space]