SideFX maintains an archive of older builds for licensed users through their official SideFX Download Page.
To run Houdini 13 on older hardware, ensure your system meets these specifications from that era: Houdini 13 Features download houdini 2014
: Houdini 13 adopted Pixar's OpenSubdiv for high-performance viewport subdivision. System Requirements for 2014 Builds SideFX maintains an archive of older builds for