Here are the specs.
So you can go up to 16GB of DDR3-1600.
There are two slots...so you would get two sticks of 8 each if you wanted to go to 16 GB.
....or two sticks of 4 each for 8 GB.
Specs are below.
Memory upgrade information
Dual channel memory architecture
Two 240-pin DDR3 DIMM sockets
Supports the following:
PC3-12800 (DDR3-1600)
PC3-10600 (DDR3-1333)
Supports 1 GB, 2 GB, 4 GB and 8 GB DIMMs
Supports up to 4 GB on 32-bit systems
NOTE:
32-bit systems cannot address a full 4.0 GB of memory.
Supports up to 16 GB (unbuffered) on 64-bit computers
NOTE:
Maximum memory shown reflects the capability of the hardware and can be limited further in the operating system.