When setting the reference voltage for the steppers.
0.55 is the sweet spot do not go over 0.6 as this will cause them to over heat and cause problems.
The newest version of repetier for the K8200 is in this link 0.95F
It has the ini files and drivers as part of the install so you can skip the install of 0.84 in the manual. http://www.k8200.eu/downloads/files/downloads/setup_repetierhost_k8200_0_95f.zip