Dont do that.
 
There is a better way.
 
First make a backup of your power config!
 
Run command prompt as admin and type in the following command.
powercfg /qh > powerconfig.txt
 
Now navigate to C:\Windows\System32 and do a search for powerconfig.txt
 
Backup that file!
 
 
Now there are a few options here to turn off CPU Core Parking. I recommend the simple GUI called ParkControl.

 
There is NO REBOOT required. This can let you easily test your system with or without CPU core parking. You might consider turning it OFF in High Performance (or similar power profile) and leaving it ON for Balanced or Power Saver. It is up to you.
QUESTION: What is that NUMBER that is shown on the GUI? That is the % of cores that *must* remain *unparked*.
Download ParkControl 32bit    Download ParkControl 64bit
 
ParkControl is now integrated into Process Lasso v6.

• Optimize processes, cores, and power consumption
• Boost PC responsiveness during high loads with ProBalance 
  Automatically restrain monopolistic, out-of-control processes 
• Energy Saver lets you run full throttle, while conserving power when idle
• Automate and persist process settings, power profiles, and more!
• Tiny footprint, using a stand-alone core engine written in native C++. You'll have no complaints about resource usage!

 
 
You can also add the parking option into the windows power options with this registry tweak

 
 

 
Shortly after AMD's Bulldozer platform was released performance was substantially increased after CPU Parking was disabled. Microsoft has later issued a hotfix to do just that for Windows 7 and Windows 2008/R2. More information, and the hotfix, can be found here: KB-2646060. User reports seem to indicate a similar issue exists on Intel i7 CPUs, and likely other modern multi-core processors. Windows CPU Parking seems just too aggressive, by default. The good thing is that you can use this tool to enable it in High Performance mode, but keep it in use in other power profiles. You can also compare and contrast the effects of disabling it in real time.