A while back, I salvaged a good eMac motherboard from an eMac with a fuzzy CRT screen. I didn't write down the specs or serial number from a screen view, or from the label on the inside of the eMac's optical drive door. Now I wanted to figure out if this was a USB 2.0 logic board, or a 1.1 USB version, but nothing on the face of the board would answer that question. There is a serial number on a paper label on the logic board, but I don't think it corresponds to the number that would have been on the drive door. This number is followed by this information: 630-4801 CHINA MLB 1GHZ. Elsewhere on the logic board is this silkscreened information: APPLE COMPUTER INC. (c) 2003 820-1521-A. I don't know that the 2003 copyright is determinative since the board layout may be the same but components on it might have changed. So how did I "crack the code"? I was about to post a question here right after registering but while gathering the info I was going to post here I figured the answer out for myself, so thought I might as well share what I had learned. I was pretty sure that there were two versions of the 1ghz board, with one (logically the earlier) taking PC133 DIMMs, and the other (later) one taking DDR RAM. I confirmed this by going to the Apple site and checking the specification pages, and found that the earlier version (introduced 2003) took PC133 and was USB 1.1, with the later version (introduced 2004) taking DDR RAM and being USB 2.0. This board's DIMM slots are keyed for PC133 RAM, not DDR RAM, so it is a USB 1.1 board. Not the answer I wanted, but at least now I know. The bottom line is that when trying to distinguish two similar boards, look for the kinds of hardware differences that might distinguish one model from another, and combine that information with what is on the Apple site (probably makes more sense to check the site first so you'll know what differences to look for!).