In simple terms, if you have a single Fast stick of RAM. Then a single Slow stick of RAM. The Faster RAM, will operate at the speed of the slower RAM. Thus if you mix any kind of RAM togather, its going to work at the slowest RAM's rate.
Thats pretty much the biggest reason why people DONT do this. Because your better RAM, becomes pointless. So if you went and paid for 1 stick of really good RAM. Then you got a crappy stick, for w/e reason. You just wasted your money. Because your system will NOT utilize the fast RAM. I dont suggest anyone mixing RAM, even the same type from different brands. Because your RAM will become handicap...
Finished With TF.