The Original Ralph :
some info on your build would help, ie what cpu and full specs
but 70C isn't that hot
most of intel's cpus start to throttle some at 80C and at 100C throttle dramatically to save the cpu from frying
To my knowledge, all "K" and "non-K" Intel "Core" CPUs since around 2008 have throttled at 95-105c (depending on the generation). I believe there may be a few low power models, such as "S" or "T" which might have different Tjunction max temperatures, but as a general rule desktop Intel CPUs will not have their performance affected until around 100c.
Shutdown does not occur until ~130c.