The LCNP4(x) uses the faster 68040 microprocessor and has 16 MW of memory. A connection for a GPS time sync source for controlling the LCN time was introduced with the LCNP4G and continued with the LCNP4M. The LCNP4M introduced a shorter board and support for 3.3 volt PCI-X sockets.
LCNP4(G)(M) can only be used with GUS release R110.1 or higher. Newer PC's with space restrictions or 3.3 volt PCI-X slots will require the LCNP4M.