It depends on the FX processor.
Basically, AM3+ motherboards will fit them. However, you must be sure about it's max supported TDP, as there are FX's processors with a TDP of 95W and others with 125W.
You can check the compatibility at the manufacturers' site.
About the nVidia GPU. Any modern MoBo that can fit a FX will this sort of GPU. Some may have an older PCI-E "version", but this is most of a nonissue in 99% of the cases.
The same goes for the RAM. If it fits a FX, it fits DDR3 RAM. Be sure about the clocks, though.