FPGA is that any good?

[epixoip]

since hashcat 3.0v started to support fpga

hashcat 3.00 did not "add support for FPGA"; it added support for any arbitrary OpenCL device on any OpenCL platform. This opens up the possibility of using devices like FPGAs and DSPs with hashcat; however, this is heavily contingent upon the availability, quality, and maturity of an OpenCL SDK for these devices. Right now, there are no competent OpenCL SDKs or runtime libraries available for FPGAs. Altera's OpenCL is garbage, and Xilinx's is alpha at best. 

why does it fall on multiple hashes,attack,algorithim?

Because RAM.