Q. What are the differences between the motherboards?
A. Xenon- No HDMI, first xbox produced. Tends to overheat very quickly. Has 90nm CPU and 90nm GPU. Produces ALOT of heat.
Zephyr- Same as Xenon, but this one has HDMI.
Falcon- Has HDMI, Doesn't overheat as much as the xenon but still gets kinda hot. First, actual motherboard revision when dealing with infamous RRoD problem. 65nm CPU 90nm GPU
Opus- An opus is just a falcon without HDMI.
Jasper- The first REAL breakthrough against the RRoD problem. This xbox sports a fancy 65 nm CPU and new 65 nm GPU. However, Jaspers are quite rare and go for a lot of money.
It means the motherboard revision the console has. As every xbox does not have the same motherboard. Jaspers are particularly rare xbox's so that is why you might find them priced higher then others.