Kingston Hyper X Genesis 2GB - Pair of 2 for a total of 4 GB of RAM

From the Kingston website: HyperX modules are specifically engineered and tested for higher speeds and lower latencies. Kingston® HyperX Genesis sets the standard for high-performance memory, offering greater thermal performance, higher frequency speed and lower latency. It is ideal for gamers, enthusiasts, system integrators and anyone who wants to maximize their hardware. KHX1600C9AD3/2G 2GB 256M x 64-Bit DDR3-1600 CL9 240-Pin DIMM