I have several Dell, Compaq that are 700mhz and up and take the following modem

ENF656-ESW-AGPR Agere (Lucent) chipset V.92 56kbps PCI modem


When I try modem in a 400mhz and less, the modem will not detect. I have several old IBMs that are 350 mhz that I would like to use this modem. Could anybody tell my why the modem will not work. The only thing the system requirements say is compatable with Win98SE WinME Win2 etc, etc.