ok, firindsquad.com says "Before 815EP was released, two versions of the 815 chipset existed, the "plain" 815 and the more advanced 815E. Both variants use the same graphics memory controller hub (which connects the processor to the system graphics and memory), the 82815 chip, the difference lies in the I/O controller hub (which connects the IDE controllers, USB ports, PCI cards, etc to the graphics memory controller hub). While the 815 chipset utilizes the 82801AA I/O controller hub, the 815E employs the 82801BA I/O controller hub. The key addition to the 82801BA (and the 815E chipset) I/O hub is full support for ATA/100, the fastest IDE hard drive protocol to date. "