Low Profile eXtensionLPX (short for Low Profile eXtension), originally developed by Western Digital, was a loosely defined motherboard format (form factor) widely used in the 1990s. A file extension is the characters after the last dot in a file name. What is LPX file? LPX filename suffix is mostly used for LaTeXPiX Script files. How to open LPX files. LPX file? We collect information about file formats and can explain what LPX files are. LPX (Low Profile eXtension) is a motherboard form factor developed by Western Digital in 1987, that was used in the late 1980s and throughout.