How to fix missing RAID1 drive

After reading the manual I discovered I had to download the "AMD RAIDXpert" utility from here. Using it I was able to "rebuild" the array by adding the out of sync disk back into the logical device.

Thanks for the tips @moskito-x, I did learn some stuff by following the steps you suggested.

Edit: Updated RaidX download link: http://support.amd.com/en-us/download/chipset?os=Windows%207%20-%2064

Set the automatic rebuild option

Rebuilding can occur

any time one or more members of the RAID 1 mirror set become out of sync, that is, the data on a drive doesn’t match other members of the set. When this occurs, the rebuild process will begin, assuming you selected the automatic rebuild option during the RAID 1 mirror set creation process.

In the RAID management system.

From there you can examine the RAID array, identify which of the two disks is faulty and which is still good. If there is ANY confusion here, do NOT proceed.

But there usually is a process to restore the RAID1 array by simply copying EVERYTHING from the good disk that still works to the other.

Look at the BIOS

Your BIOS port mode must be set to use RAID (not IDE Emulation, or AHCI, etc.). Set it to the same as your first harddisk.