Enter the BIOS. Go to the Advanced tab. Under CPU settings change "C7 state" from auto to enabled. My CPU was only hitting 4.3Ghz until I changed this setting. All cores are hitting 4.7Ghz now.
 
I hope this is something that can be fixed with a BIOS update. It seems odd that if I use XMP I have to enable the C7 setting instead of auto working.  There has to be a lot of people experiencing this problem I assume.
 
I got the answer from here:
https://communities.intel.com/thread/121238
 
I hope this helps.