Welcome to the forums.
First, a note about forum netiquette: We consider all caps to be shouting and it is very rude.
Like slicedtoad said, you should be able to downclock the RAM and it should work. But here is why we need the motherboard and RAM details: motherboard makers publish a QVL (Qualified Vendor List) of memory that has been tested to work with that particular motherboard. That is the good news. The sort of bad news is that if a particular memory doesn't
appear on the QVL, it doesn't mean that the memory will not work. It may just mean that the memory wasn't tested.
But generally, if you find similar models of the same brand on the QVL, what you have should work.