Figured it out was the mini SAS cable after all:
Apparently we were using a type CL2 cable thinner than the usual and when switched to a type CMG cable the thicker type we got through-puts of 1600 MBs raid 0 and 1200+ raid 6.
Nir Shelter
Data Wrangler/DIT/3D Engineer
http://www.datashelter.com.au