More Information:

I've got two sets of these for a total of 8GB

G.SKILL Ripjaws Series 4GB (2 x 2GB) 240-Pin DDR3 SDRAM DDR3 1600 (PC3 12800) Desktop Memory Model F3-12800CL9D-4GBRL - Retail

Brand G.SKILL
Series Ripjaws Series
Model F3-12800CL9D-4GBRL
Type 240-Pin DDR3 SDRAM

Capacity 4GB (2 x 2GB)
Speed DDR3 1600 (PC3 12800)
Cas Latency 9
Timing 9-9-9-24-2N
Voltage 1.5V
ECC No
Buffered/Registered Unbuffered
Multi-channel Kit Dual Channel Kit
Heat Spreader Yes
Features Compatible with Dual Channel Intel Core i5 CPU for P55 chipset motherboard, Dual Channel Core i7 CPU for P55 chipset motherboard, and AMD AM3 Platform.