The A2 error code called IDE initialization is just old terminology, and just refers to a SATA chipset having an error, regardless of the mode. If your CPU is Ok, my guess is you have a drive connected to the ASMedia chipset. Those ports on at the top of the stack of SATA ports, as you look at the board mounted in a case. You can't use those ports on a new build until a driver is installed. Use the Intel SATA ports only when first starting the board and installing the OS.
You'll need to clear the BIOS/CMOS after that error and removing drives from the ASMedia ports.