I have the latest BIOS for DX58OG installed, my boot device is a RAID 0 volume, legacy boot (UEFI Boot disabled).
With "General Optimization" (supposedly speeds up booting) enabled, the system fails to boot from the RAID 0 volume. The RAID BIOS initialization screen doesn't show up, the AHCI BIOS initialization screen does, the the system ends up with a "Cannot Find Boot Device (sic)" error.
The description in the BIOS setup program says that RAID BIOS initialization screen not appearing with "General Optimization" enabled is normal, but that RAID volumes should still be bootable. However, that's clearly not the case.
I understand that when you have the boot optimization on the system is not able to boot from your array.
The problem that you are experiencing may be caused by the spin-up time of your hard drives. Remember that the hard drives need to be ready before the controller tries to read them.
If your hard drives require a lot of time to become ready, you may encounter this problem.
You can try to get in the BIOS and under the configuration tab, SATA configuration there is an option called hard drive pre delay, change this to 3 and try to boot.