Sorry mate I doubt it's to do with it being SATA or even AHCI.
I have just checked my Laptop (HP DV9299EA), all 3 channels show as having a device connected (2 SATA HD's and a SATA DVD), the 2xHD's are running UDMA 5 and the DVD Multi-Word DMA 2, the system is running Vista Home Premium.
My old system, which used to be my main system before I upgraded to the UD7 has 2 HD's and 2 DVD's all SATA, the mobo is a Crosshair and it's running Win7 Pro 64bit, once again if you right-click on each controller and go to the advanced tab it will tell you whether a device is connected, what mode it is running in and you can enable\disable DMA.
Something is clearly not correct on the system using the UD7, it is the first system I have ever known where the ATA\IDE channels didn't show a device connected and the mode is was running. I don't know if it is a driver installation issue or what but something is wrong.