Well, this is clear that ALL informations from the computer must walk through the CPU,also all rendered textures,etc.
It is also clear, that normaly there isnt a problem in 100% cpu usage, you are right. Only when the Temperature of CPU or GPU is to high.
However I have learned in school,that the life of a CPU is shorter, when they work permanently at 100%.
(ITS like a car, which you ever pusehd 100% gas=> New car isnt a problem, but later and later you will see the difference

)
Its like the RAM in computer. Normaly if you have a new computer, you cant see that, but if you have an older computer and play every day Windows Chess for example

and than playing 8 hours without break such big game and when you will play a game next day, the computer peeps and the Ram Module is destroyed

(Because the life of this module was soo long and when it gets than a really big work, than it will be destroyed)
However I´ve learned that in 10th grade in school,so maybe the teacher werent that intelligent, i hadnt hear anything about similar things from that time,too.
Lewin, could you check your messages.
pawel95