Hi, I don't know if you have the same modules, but I recently bought these: http://www.ocztechnology.com/products/memory/ocz_ddr3_pc3_12800_gold_low_voltage_dual_channel
These are rated at 1600MHz, 8-8-8-24 timings at 1.65V.
But when I put them in, they were also running at 1066. I manually gave in the speed, timings and voltages, as the RAM advertised they were rated for. Normally that shouldn't give you any problems.
JUST make sure that your motherboard supports RAM at 1600MHz before you do!