ASROCK 775DUAL-880PRO Manual To Installation And Configuration page 10

Create RAID 0
If RAID 0 array is selected in step 2, user can also select a block size
for the array. Use the arrow key to highlight the "Block Size" and
press <Enter>. Then the list of available block size will popup. The
block size can be selected from 4K to 64K Bytes.
Use the arrow key to highlight the Start Create Process and press
<Enter>, then a warning message will appear. Press Y to finish the
creation, or press N to cancel the creation.
Important note:
The content of the hard drive will be destroyed after array creation.