Usually fans will spin at 100% when there is some kind of sensor error.
Did this issues occur together or what? What is the timeline on these issues? How long has the CPU fan been going 100%?
What do you use this computer for? Are you just trying to keep it alive out of nostalgia or do you actually use it for something?
i7 7700kK @4.2ghz
16GB DDR4 3200mhz
GeForce 1080 Ti