ADATA XPG V 1.0 DDR3 1600Mhz 8 GB Kit (2 x 4 GB) CL9 Desktop Memory AX3U1600GC4G9-2G High quality 6 layers PCB (Printed Circuit Board). Backward compatible with DDR3-1333 and DDR3-1066. Optimized for 64-bit OS (operating system). Test at latency settings 9-9-9-24 at 1.55V-1.75V. SPD (Serial Presence Detect) programmed at JEDEC standard DDR3-1333 with latency settings at 9-9-9-24 for basic system booting.