Ok, so I figured out how to turn off the high pitch. It's coming from the CPU and it is a problem that MANY laptops and PCs are facing. Solution: http://asusnoise.blogspot.co.uk/ (it works for all other ASUS laptops that have this problem).

Nonetheless, the solution to the problem makes new problems:

Processor Idle Disable function, when its active, regulates the CPU usage. Thus, our CPU can work e.g. on 3% of capacity. But, if I set it Disable, the CPU momentary hits 100% usage, and allocates all available resources to every process (e.g. suddenly Firefox starts to drain 60% of CPU power, and calculator 40%). Apart from obvious power waste, in case of laptops there is another problem: the fans will start working constantly at the "full throttle", thus its much more loud and annoying that the screech I was tried to eliminate...

Any bright ideas? Is there any fix to this Processor Idle Disable problem? Or should it be like that?

PS: the easiest way to deal with the problem is either work on battery, or switch to Power Saving program - both of them immediately eliminate the issue.