OCZ OCZ3X16004GK PC3-12800 DDR3 1600MHz Intel Extreme Edition 4GB Dual Channel Kit DDR3 1600MHz XMP Profile 1: 1600MHz 7-7-7-24 XMP Profile 2: 1800MHz 9-9-9-31 Intel Black XTC Heatspreader Optimized for Intel X38/X48 Chipset