No 1866 option. bclk is set to 200 so it goes 1200 to 1600 to 2000 to 2400. My hands are tied.
If you are testing for a RAM OC you should play with Bclk so you get more precision. You won't learn much about your RAM's max OC by keeping Bclk fixed at 200 and jumping the RAM multis.
And as was said VTT needs to be within .5V of DRAM voltage.