The current and only version of firmware for the 330 SSD is 300i, so no update exists.
What are you using as a benchmark/test program? Results vary depending on the test software.
The AMD SATA III chipsets do not perform quite at the level that Intel SATA III chipsets do. It also seems the AMD RAID setup and settings are somewhat complex and require more adjustment than Intel RAID. I suggest checking the AMD forums, which you probably have done already.
It usually helps to have your SSDs connected to the first four (in your case) SATA ports, but I believe I read that moving the connections can cause problems with AMD RAID, check that before doing so.
Are you using the latest AMD RAID driver and RAIDXpert software?