AMD FM2 Chipsets
The A55 has SATA 3 Gb/s support and supports a single VGA slot. The AMD A55 clearly targets signage boxes and, perhaps, light office clients. It is meant to be used with both A6 and A4 APU products.
The AMD A75 offers SATA 6Gb/s support (six ports in total are supported natively), adds FIS-based switching for those SATA ports, and has native USB 3.0 support. The AMD A75 is really for mainstream users, like your mom or dad who are also interested in snappy drive and external device operation, thanks to native USB 3.0 and that SATA 6 Gb/s support; it is obviously geared towards both A8 and A6 APUs.
The AMD A85X supports eight total SATA 6 Gb/s ports with FIS-based switching and adds in CrossfireX support. The new AMD A85X targets gamers and enthusiasts, and those that like to keep up with the latest and greatest in technology. AMD's intention is for you to pair this chipset up with AMD A10, AMD A8, and "K"-level, "Unlocked" APUs.
In the end, it's pretty basic. Each chipset, or Fusion Controller Hub (FCH for short), has its specific use and, thereby, a specific target market. Those that don't need as much can pick a chipset that doesn't give them as much while, at the same time, saving money through features that chipset lacks. It looks like you might get exactly what you pay for. The AMD A85X is AMD's high-end chipset. AMD sent me the above block diagram of its FCH functionality. It shows all the features and which part of the platform, whether APU or FCH, supports which features. These essentially remain the same as they were before, with the changes the new AMD Elite A-Series APUs bring forward.