Asus Maximus VIII Hero - newbie questions

[ReaperXFS]

So I assembled myself a new PC - Asus Maximus VIII Hero, I5 Core 6600K, G.Skill RipjawsV F4-2800. And I have some newbie
questions.

My first question is: The CPU keeps changing frequencies between 800Mhz to 3.9GHz. I mean it doesn't change them randomly, but when idle goes to lowest possible and when playing games to highest possible. First I thought it was because AI Suite 3 and it's
performance optimization stuff, but I reset it to defaults. I also reset everything in BIOS to optimized defaults. I think its probably
some sort of energy efficiency thing. But how do I turn it off, it is really bugging me? I want the CPU to work at its 3.5GHz to
3.9GHz Turbo frequencies only.

Second question: Is it normal that different applications use exactly 25% CPU per application? I mean for example Viber uses 25%,
uTorrent uses 25% while downloading something and 50% idle.

Keep in mind I never had an Intel powered PC before. My AMD configs never did stuff like that.

[Menthol]

Intel Speedstep, it is supposed to do that, saves energy and produces less heat when not in heavy use, you can disable speedstep and C-states in bios, or easier to set windows power plan to performance in Windows

[Janne-71]

In my oppionion it's just good thing to lower clock speeds when it's not needed. I think it can be adjusted also from power plan settings...there are settings for processor speeds...lowest % etc. atleast on Windows 10.

[Chino]

Your system is working exactly like it should. No worries.