Having a quick Internet peek, while the CPU is old by computer standards (Q4 2012), its specifications should be enough to run Arma 3. Its L2 cache is kinda meh, but still, it should run. A little more information would be helpful, though!
Is it crashing at any particular point, always at that same point? On load up, middle of a mission, etc? Are you running the game vanilla (no mods), or with a collection of mods?
Have you looked at your RPT to see if anything specific is mentioned? If you don't know how to find them, it's pretty simple. Opening up the run command, type in: c:\users\"what your pc is named"\appdata\local In that, you'll see an Arma 3 folder. In that folder you'll see the RPT files. Should be sorted by date, so just open it up (default is notepad), and see what it's saying.
