Although size and shape are exactly the same the A1181 has changed boards with the years. It’s not a matter of speed only, small connectors on the board have been modified too. A 2009 A1181 board doesn’t fit a 2007 machine. To be on the safe side I would suggest to always ask seller about compatibility. The board number changed at least 3 times with the years and every release introduced variations. Sticking with a board of the same release would surely grant compatibility. Board numbers read such as 820-xxxx-x