What model CPU do you have? and is it Sandybridge or Ivybridge?
* To support DDR3 1600 MHz, you must install an Intel 22nm (Ivy Bridge) CPU.
* To support XMP memory, you must install an Intel 22nm (Ivy Bridge) CPU. k
(Go to GIGABYTE's website for the latest supported memory speeds and memory modules.
The RAM will SPD detect at 1333 and should run with a sandybridge as long as XMP is not enabled.
Start by testing with two DIMMs - Pair should be installed in the white slots
Now disconnect your system from power and perform a battery pull. If there is a CLR_CMOS button or jumper you can perform this as well according to your manual.
Does the system POST with 2 DIMMs and setup defaults?
You may need to resort to manual settings.