In very basic terms, both the i815 and i815E motherboard chipsets are simply enhancements to the venerable Intel BX. These additional features include AGP 4X, ATA-66/100, PC133 support and true 133 MHz operation with standard AGP and PCI speeds. Other features are support for quad USB ports, integrated 2D/3D video (with optional 4MB display cache) and AC '97 sound, along with a CNR slot for low-cost modem, sound and LAN add-in cards.

The i815E's PC133 memory speed really only comes into play when using a CPU that runs on the corresponding 133 MHz FSB, and with 100 and 66 MHz processors, the i815 and i815E use a standard 100 MHz memory speed. The i815 and i815E are also built solely around the FC-PGA socket, so do not bother looking for a Slot 1 variant.

When examining the specs on a new motherboard, keep in mind the differences between the i815 and i815E chipsets. The i815E (E stands for Enhanced) adds a brand new Southbridge chipset to the original i815 mix that incorporates ATA-100 data transfers, Quad USB support and integrated LAN capabilities. The i815 and i815E share the same Northbridge chipset so there are no differences concerning CPU and memory functionality.

At first glance, the AOpen AX3S Pro looks to have a standard i815E layout, but a bit closer examination yields some interesting differences. The size of the board is the first point of interest, as it checks in at 9”x12”, which is a bit wider than the standard i815E motherboard. This extra width is probably due to some design decisions that we will get to a bit later in this section. The AX3S Pro has a 1 AGP/5 PCI/1 CNR slot layout which should offer enough expandability for most users, but is still one less PCI slot than is commonly found with the i815E. The jumper and on-board connector arrangement is clean, with the only possible issue being Audio and CD lines, which are just a bit too close to the AGP slot.

The AX3S Pro features 3 DIMM sockets supporting a maximum of 512 MB of system memory. Though the 3 DIMM sockets may hamper future memory upgrades, the double-sided DIMM limitation of the i815E serves to limit system memory to 512 MB under most configurations. Unlike many other i815E motherboards, the AX3S Pro has ample room between the AGP slot and DIMM sockets to facilitate memory upgrades or removals. This is also one big advantage of going with only 5 PCI spots. The board also has a DRAM LED indicator that can diagnose memory problems when the PC first boots.