RAID-10 with 6 disks using RST?

Hello,

I currently have a Rampage V Extreme on the X99 chipset and was wondering if there is a way to create a 6 disk RAID10 using Intel RST? For some reason, it only allows me to select 4 out of the 6 hard drives. They are connected to the correct SATA ports and show up in the Intel RST prompt. When I select a fourth disk, the other 2 get grayed out though.

Any ideas?

Thanks