2 x 1.5V DDR3 DIMM sockets supporting up to 32 GB of system memory
Dual channel memory architecture
Support for DDR3 1866(O.C.)/1600/1066 MHz memory modules
1.2 x 1.5V DDR3 DIMM sockets supporting up to 4GB of system memory (Note 1)
2.Dual channel memory architecture
3.Support for DDR3 1666 (OC)/1333/1066 MHz memory modules
In laymen terms you can stick two sticks of 8GB of RAM in with a max MHZ of 1600MHZ.
2 x 1.5V DDR3 DIMM sockets supporting up to 32 GB of system memory
Dual channel memory architecture
Support for DDR3 1866(O.C.)/1600/1066 MHz memory modules