I never said tracking down datasheets was easy, just that it is usually the most authoritative source.You'd think that would be easy to know but it took a look at AMD to find that the FX was the 'Bulldozer' architecture which Wikipedia says is an X86-64 architecture so it looks like its 64 bits. You didn't say which OS you are looking at but Microsoft has utilities that suggest an OS version by inspecting your hardware - even though its going to want you to run Win10. Maybe Linux has something like that, too. Otherwise, a specific search (can I run Debian Linux / Win 7 home on an AMD FX xxx with xx Gig of RAM) should get you some useful stuff.
Note in the Wiki article that there are some differences in x86-64 architectures between Intel and AMD - minor but worth knowing about.
Good luck in your search.
It's an AMD quad core processor so whether it's running 2GB or 4GB of RAM which is likely it will run a 64 bit OS but depending on what the system is expected to do will impact on speed.It really depends on the hardware ... If you have 4gb max of ram then 32bit would best but if you want to use more that 4gb then run 64bit..