Woogie 
look at the sockets on the motherboards. If they're 2" squares and say like "socket 2, 3, 4, 5, 6, 7", they're a higher grade than most scrap buyers see many of these days. If the socket numbers are higher(like in the hundreds) and smaller than 2" squares, they're newer. If there aren't any square white sockets, and have several black slots on them, the longer black slots might be getting you into the "vintage" era.
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