AMD used to have SB600 drivers on their website however, while still having the option in their dropdown selection menu for 6-series, when you get to where to download the driver, it will only support 7-series and higher; and that is not just the txt on the website, running the driver will produce a fail as it will not install.
Now...if you download the driver from your mobo manufacturer, and the one from AMD's website, and allow them both to unpack, you can open up the .inf and copy your information from the mobo manufacturer into the newer driver. That may allow you to use the newer AHCI/RAID driver when "F6'ing" (or chosing Load Driver or whatever it is in the initial windows setup). When you do the stare and compare, you'll see your mobo driver inf and new driver inf have a lot in common, just copy the devices the old driver has but the new doesn't into the new driver inf. Save to USB stick and try that during Windows setup.
EDIT: I've made AMD aware of this, and, rather than remove the 6-series section as they aren't providing drivers that work for 6-series chipsets, or, preferably, at least post the last supported driver that supported 6-series chipsets (which would be far newer I'm sure than what the mobo manufacturers have), they instead told me to go to my mobo manufacturer and then just kept the 6-series dropdown available with a driver that doesn't work with it. Times must be very bleak at AMD to suck that bad at something so exceedingly simple...
Chuck