All the speeds marked with OC by them are technically overclocking and not guaranteed by Intel. i.e. your CPU, subject as it is to the silicon lottery, might or might not make it.
All RAM comes with a stock guaranteed basic frequency it will run at...2133 or 2400, for example, when you first boot up the board....the XMP profiles are then the OC part of the spectrum....you have to select them in BIOS
4266 by the way meant you have to change strap to 125 so Speedstep and or speedshift will not work....not allowing downvolting and downclocking of CPU at idle.
So basically you pays your money, you takes your chances with anything marked as OC on motherboard specs. 3600 is supposed to be more plug and play...though this too may require tweaking skills in BIOS.