The OS X kernel does control this directly since below 5% my CPU gets locked to 1.2GHz instead of the normal 3.7GHz so there has to be a way to control the CPU speed.
I am aware of this question (Limit processor speed like in Windows) which claimed it to be impossible but after noticing that OS X does control your cpu speed directly depending on battery power I find it hard to believe it's impossible.
So is there any hidden kext and/or kernel call to control the cpu speed? Forwarding me to kernel documentation so I can write my own app is an option as well.
Native Mavericks power management delivers the best combination of
processor and graphics performance and efficiency. The ingredients are
an installed processor specific power management ssdt, a compatible
system definition and the native power management kext. Native
Mavericks power management does not require specific BIOS settings or
anything more than one boot setting to load the power management ssdt.
Credit for the technique described to PikeRAlpha.
What changed between Mountain Lion and Mavericks power management? The
existing processor frequency/power state reporting tools (i.e.,
MSRDumper, HWMonitor) stopped reporting power states between idle and
max non turbo. This led to an incorrect conclusion that native
Mavericks power management was not working. A new tool, Intel Power
Gadget, shows Mavericks power management is working as designed.
To be clear, native Mavericks power management is not mandatory. The
consequences are not severe. Performance is similar, however, higher
temps (~10 C), more power (5-10 W) and sleep problems are likely.
v1.1 - 4/4/14 - CPU PM/Core i3/5/7 xxx (1st Generation)/Core 2 and
earlier (below) v1.0 - 4/2/14: Initial Release
OS X/10.9.2 or newer
Server, see Guide: Asus X79 OS X Controlled SpeedStep
OC, use ./ssdtPRGen.sh -f freq flag