Fiddling with the Gigabyte GA-H61M-USB3-B3 Rev. 2 - AHCI mode.
Notes:
Onboard SATA 2, x 4. Supports AHCI, IDE through Intel H61 chipset.
Onboard SATA 3, x 2, Supports AHCI, IDE and Raid uses Marvel 88SE9172 Chip.
Uses a Hybrid EFI bios, not a UEFI firmware and supports GPT disks over 2.2TB.
When setting the BIOS so that the SATA drives use AHCI mode, you can set the SATA settings to NONE for the devices on the SATA 2 ports so the BIOS doesn't try to identify them and the PC will boot a bit faster. Later a second AHCI firmware? loads and identifies them.
HOWEVER, you cannot do this with the devices on the two SATA 3 ports (Onboard GSATA3). See below.
In the BIOS settings, under Standard CMOS Features, you can see IDE Channel 0 Master through 4 Master and a final Channel 4 Slave. The first four, 0 through 3, are for the SATA2 connections. The last two, Channel 4 Master and Channel 4 Slave are for the GSATA3 connections. If you set the last two IDE channels to NONE, and your boot drive is connected to the GSATA3 controller, your system won't boot. These last two channels aren't controlled by that AHCI firmware that loads later. They have their own settings for AHCI found under Integrated Peripherals.
Next, under Integrated Peripherals, you can set the SATA controllers to AHCI mode.
The first item, SATA AHCI Mode, sets the AHCI mode of the SATA2 connections attached to the Intel H61 chipset.
To change the SATA3 controller for devices on the last two IDE channels, find, GSATA3 Controller - this is the Marvell 88SE9172 Chip, toward the bottom. You can then set GSATA3 controllers to AHCI mode.
Before installing an OS, make sure the BIOS/UEFI SATA mode is set to AHCI.
