Hi there,
Welcome to the wonderful world of SSD's on the AMD platform. I too have been encountering the lovely speed reporting issues that you have come across with my own set-up.
After a lot of exchanges of e-mails, testing various firmware updates and different configurations with ADATA, the manufacturer of my SSD's, it seems that it all comes down to the benchmarking software used.
In our testing we used CrystalDiskMark, ASSD, HDBench and ATTO and we found that for SSD's you should really only use ATTO for benching as this has proven to be the most accurate.