Tyan is really focused on cost. They have an older, "cheap" 2-way Opteron mainboard that doesn't even put DDR channels on CPU #2.
And several manufacturers are even worse than Tyan. Especially the non-server focused vendors. SuperMicro and Tyan are better than most.
But still not the quality in mainboard design you'll get from select Tier-1 OEMs like HP and Sun.
So what is the bottom line? None of the common board makers such as Asus, Iwill, Tyan, Supermicro and Gigabit make a "good" board? So what should the poor server builder do?