Intel socket LGA1155 CPUs have an embedded memory controller, meaning that it is the processor, not the chipset, which defines what memory technologies you can have and the maximum amount of memory that is possible. The motherboard, however, may have a limitation as to how much memory can be installed.
The integrated memory controller from socket LGA1155 processors supports DDR3 memories up to 1,333 MHz (“Sandy Bridge” CPUs) or up to 1,600 MHz (“Ivy Bridge” CPUs). According to ECS, the Z77H2-AX supports memories up to 2,800 MHz.
The ECS Z77H2-AX has four memory sockets. Since DDR3 memory modules can be found in capacities up to 8 GB, you can have up to 32 GB with this motherboard if you use four 8 GB modules.
In order to enable the dual-channel mode, you must install two or four memory modules. Unfortunately, ECS used the same color for all the memory sockets (black) instead of using two different colors, which would certainly help users detect which sockets to use. Installation must start from the bottom-most socket, i.e., the socket closest to the main power supply connector. When installing two memory modules, you will have to “skip” the second memory socket, and install the second memory module in the third memory socket.