Usually Realtek AC'97 or C-Media chipsets on these models.
An excellent historical preservation site specifically archiving legacy motherboards. Look up the The Retro Web EPoX EP-4PGM2I Motherboard to find specific community-uploaded BIOS and driver archives . skachat draivera epox ep 4pgm2i
You can safely download legacy drivers and BIOS files for this specific motherboard on enthusiast repositories like The Retro Web EPoX EP-4PGM2I Page or TechSpot EPoX Drivers . Usually Realtek AC'97 or C-Media chipsets on these models