In general, Arnold is going to work on pretty much any 64-bit system where Houdini, Maya, Cinema 4D, or Softimage works. However, there are some minimum OS requirements:
- OSX 8 or later (as of Arnold 22.214.171.124)
- Windows 7 or later (as of Arnold 4.2.3)
- Linux with at least glibc 2.12 and libstdc++ 3.4.13 (gcc 4.4.7) (as of Arnold 4.2.6)
- CPUs need to support the SSE4.2 instruction set (as of Arnold 126.96.36.199)
Other than that, Arnold works on Intel and AMD processors, and has no graphic card or GPU requirements, since Arnold is a CPU-based renderer.