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If the machine won't boot with the stick installed, there is a good chance that the ram is faulty or dead. If you can boot the machine with another stick installed in the same slot, then that definitely suggests something is wrong with the module in question.

Eliminate the slot as being faulty by testing your other ram stick in it, if it doesn't work either, you probably have a faulty ram slot.

I'm not sure how much mac specific ram typically sells for, but in the PC world, pc2700 is more expensive than the newer stuff, but I won't hazard a guess as to the value.
 
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