[quotemsg=17673884,0,301262]C state is used for power saving and when you overclock you use the maximum power of the CPU, constantly. So you would not want to use c state. Disable both, also manual vcore always, adaptive might do some adjustments you don't want to happen.[/quotemsg]
First off an overclocked processor does not use maximum power constantly. I'm on a overclock processor right now and it step the frequency down when the CPU isn't under heavy usage. This is called Intel Speed Step and it's been around for awhile.
Disabling C-States can help with stability but it isn't likely to help if you aren't doing anything extreme. Disabling C-States will prevent your processor from going into a low power state and will significantly increase idle power consumption.
Both manual and adaptive are good options regardless of what Gingerbread says. Both are recommended in the official overclocking guides for the 3570k, 4790k, 4690k, ect.
You might want to take a look at this Skylake guide
http://www.overclock.net/t/1570313/skylake-overclocking-guide-with-statistics