Install the ram in socket 1 and 2. This would be the closest white and blue dimm sockets to the power connector (on the motherboard)
from the manual:
Dual Channel Memory Configuration
This motherboard provides four DDR3 memory sockets and supports Dual Channel Technology. After the memory is
installed, the BIOS will automatically detect the specifications and capacity of the memory. Enabling Dual Channel
memory mode will double the original memory bandwidth.
The four DDR3 memory sockets are divided into two channels and each channel has two memory sockets as following:
Channel A: DDR3_2, DDR3_4
Channel B: DDR3_1, DDR3_3
Due to CPU limitations, read the following guidelines before installing the memory in Dual Channel mode.
1. Dual Channel mode cannot be enabled if only one DDR3 memory module is installed.
2. When enabling Dual Channel mode with two or four memory modules, it is recommended that memory of
the same capacity, brand, speed, and chips be used and installed in the same colored DDR3 sockets for
optimum performance. For optimum performance, when enabling Dual Channel mode with two memory
modules, we recommend that you install them in the DDR3_1 and DDR3_2 sockets.