ASROCK B75M R2.0 User Manual page 55

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We recommend to use Intel B75 SATA ports (SATA2_1,
SATA2_2, SATA2_3, SATA2_4, SATA2_5 and SATA3_0) for
your bootable devices. This will minimum your boot time and
get the best performance. But if you still want to boot from
the ASMedia SATA3 controller, you can still enable this in the
UEFI BIOS.
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