corsair xms3 6gb 3 x 2gb 2000mhz pc3-16000 240-pin ddr3 triple channel memory kit for core i7 platforms 6 triple channel kit ddr3 2000 pc3 16000 240-pin ddr3 sdram cmx6gx3m3b2000c9 memory corsair cmx6gx3m3b2000c9