Asus Z87-WS - Manual (Page 28)

1-12 Chapter 1: Product introduction
Chapter 1
Recommended memory configurations
1.2.4 System memory
The motherboard comes with four Double Data Rate 3 (DDR3) Dual Inline Memory Modules
(DIMM) slots.
A DDR3 module is notched differently from a DDR or DDR2 module. DO NOT install a DDR
or DDR2 memory module to the DDR3 slot.