^along with that... what AHCI/SATA drivers have you tried?
I had a similar problem with a Gigabyte board. It was picky about which driver was installed for SATA controller. Certain drivers would make the boot take forever.
Another "long boot" problem I had (same Gig. board) was a setting in the BIOS. It was a setting that allowed legacy USB boot drives. I have a USB SD card reader installed, and when that BIOS setting was enabled the boot would take 2-3 minutes because it was waiting for the SD memory card "drives" (no cards installed) to time out before loading Windows on the hard drive. That one drove me crazy for about 2 weeks until I found the BIOS setting to turn it off.