ref G.SKILL F3-10666CL8D http://www.gskill.com/products.php?index=224
1333 MHz 8-8-8-24-2N @ 1.5v
Are you using any ASUS Utility i.e. AMD OverDrive Utility or ASUS AI Suite? If so those Apps override BIOS changes made 'manually' in the BIOS.
The better choice is not to use them, and set everything in the BIOS Manually. If you're not using some BIOS invasive App then I assume that you are 'Save & Exit = Yes' once the changes are being made. Lastly, if none of the above applies then swap out your CMOS battery.