The heart of the XP4 mini-cube system is Iwillís custom miniature motherboard. The board, though half the size of a standard ATX board, includes virtually all of the functionality of a larger, standard size board. Board layout, though condensed considerably, is not dissimilar to typical ATX layouts. The S478 CPU socket and retention bracket are located toward the right rear quadrant, just in front of the ATX I/O stack. The 82845GV GMCH is just adjacent, and is cooled by a rather small passive heatsink only. While we experienced no problems whatsoever, we wonder if perhaps, given the small size of the case and resultant heat buildup, a larger heatsink would not have been more prudent, particularly for the XP4 and 845GV chipset, which produces more heat due to the internal graphics core.
Only a single DIMM slot is provided. While not at all uncommon for a system of this ilk, incorporating a second DIMM slot would allow much greater flexibility, and should not prove exceptionally difficult to accommodate in terms of board real estate.
Both the XP4 and XP4-G make use of Intelís latest ICH4, which is positioned nearer the front left of the board. Curiously, Iwill has provided connectors for two (parallel) IDE channels, as well as a floppy connector. Serial ATA support is not provided at this time. Given that the XP4 only has two drive bays, only one of which is external, it seems highly unlikely that the floppy connector will ever be utilized -- that would mean no CD drive could be installed. Additionally, since devices in both bays can be accommodated by a single IDE cable and channel, one of the IDE connectors could likely be done away with as well. Those two exclusions could perhaps afford the extra PCB space needed for the second DIMM slot we mentioned before.