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#31
There is no disadvantage to buying RAM rated for a higher speed, except you will pay more for it. Remember, the "speed" of the RAM is the maximum speed the RAM is rated for. There is no harm in "underclocking" the RAM, though the extra money you will pay will be wasted.
I don't want to make a statement saying that OCZ's suggestion is a load of bologna, because I'm sure they know that kind of thing way better than I do. However, I would take Intel's advice in this situation, especially seeing as you are currently having problems.
If I were you, I would buy some 1.5v 1066 DDR3 RAM, from a reputable company such as OCZ, Crucial, etc. Newegg ratings are helpful too.