alot of website has disclaimer

let me give u anotehr example:
for example lets say honda SX-100 should be use 500hp (on website), but the one in car dealer is 400hp, is it ok? and the price differ on it to justify

apply that to motherboard:
alot can be same model or serial number but the revision is different, like asus TUV4X revison 1.2 can use full 2GB ram, but 1.1 can only use 1.5GB, however the website can say it can use 2GB.

try to apply mobo to car or to video card

many company can dismiss as different revision or website not updated, as long as they hide behind the sheild of disclaimer. (think as Tripex 9550 card as "NEW" revision")