Corsair TR3X3G1600C8D 3GB (3x1GB) DDR3 : PC-12800 (1600MHz) DDR3 For X58 MB/i7 Core, 3x240-pin DIMMs, Triple Kit, 8-8-8-24, 1.65V.
1600MHz for the P6T is classed as overclock, the ram above would clock a little further by changing the Blck but not as far as 1866Mhz. It gives you tri channel...