@DGroves. Thanks for the info. Yes I read the specs and documentation prior to posting. I understand the z820 only has 2 6gb/sec ports on the intel c600 sata controller. That's why I'm running the other RAID 0 pair on the LSI chip, since it's advertised as 6gb/sec. Although on the Broadcom site it contradicts the product brief with SATA 3gb/sec listed... The cables I'm using are 12" SATA 3 cablemod brand cables. Is there a way to access the LSI Mustang chip for some information on if and why it's down stepping the speed? Using software to query the interface I can't see the RAID array on the LSI chip ( I can on the intel chip).