What and how many cards are you using? I-18 seems quite high for my card but I'll try with I-13 first
I'm running just one R9 290.
Make sure you configure shaders number properly, and you can pump Intensity as much as you can, as long as machine is not crashing or getting HW.. And don't set anything else, at least on first try, let it configure itself and see how much KH are you gonna get with that autoconfig...