Reference clock is your HTT....so naturally by default it's 200.
Memory divider....it's whatever you set it dude lol. If you've left it stock then it'll be at 200 also. This is what you'd have it set in the BIOS. Basically this is allowing you to figure out the best combination of HTT, memory divider, and multiplier and whatnot.
So in my case I wanted to try to get my RAM around 233MHz, I kept playing around with it, until I found out that setting my HTT to 285, memory divider to 166 would give me 233MHz for my RAM to run at (DDR466) and my CPU at 2.565GHz which is basically where it caps out.
My main point was to show you how your memory is effected when using a half multi like 13.5
So for you, if you left your HTT at 200, and changed the multi to 13.5 for 2.7GHz, your memory would be running at 192MHz even though the memory divider is still at 200.....that's the effect of the half multi.