Hi mate

VTT can also be CPU and board related also. I would suggest trying to use 1.64vdimm from 1.5 its on currently and see if it allows you to lower VTT. The other thing you should look into is enabling turbo so that the CPU jumps to 21x multi hence using lower BCLK....btw BCLK does nothing for performance if you are thinking you need to have it high

also odd multies tend to be a bit more stable than even on Bloomfield

the OC looks good mate