Hello
Your ram is not being downclocked as you call it. 1333Mhz is the Intel spec for the board. To have your ram run at the ram manufactures top rated specification you will have to overclock the ram. Not a safety feature rather a design standard.
However that does not mean we can not overclock and get your ram to the specified frequency. The real world gains you will get out of an increase from 1333MHz to 1600MHz is hardly noticeable in the real world to be blunt unless you bench. But if your system can handle it lets make it happen.
Yes you are spot on the amount of ram and the total number of sticks of ram in system will make the overclock interesting.
May I make a suggestion please save your current working overclock settings as an profile. That is important. Even better is take a series of screen shots and save them some place so that if or when you update your BIOS you will have a record of your settings that you can fall back too.
To start what is your current settings for the ram and include the voltages that are not on auto please.
To help us help you - please provide as much information about your system and the problem as possible.