dr.zli: if the cooling is adequate you are ok, kill temperature for any processor is around 90-110 degrees celsius and most modern motherboards will auto shutdown the system if the processor starts to overheat. Your problem might lie in fable 3 being a console port and relying more on CPU than GPU for rendering, but I might be wrong since I don't own it. Normal cpu cycles when idle should be from 1-3% on any core, most games i play on my quad core either use only one to the max or when optimized for multicore operation they use up tp 40% of all the cores in the tast manager.
Hope this helps

Sirkenneloth: You are right dont doubt yourself. The port is the problem, got the same problem with games that are ported.

nyx: It's quite common for a game to use 100% cpu. Intel Core i7 has a tempereature cutoff at 95-100C, it' will then begin to reduce the cpu clock. It this doesn't help the computer will simply blackout/shutdown to protect it self from temperature damage.

And by accident i know it works, temps reached 100C then the clockspeed went down.

But it helps cleaning out dust from heatsinks and fans atleast once every year. Even if computers made the last 5 years are protected against high temperatures. As it will reduce noiselevels (higher fan speeds to maintain same level of cooling), and improve performance if the heatsinks are so clogged the cpu tempereature reaches the cutoff.