I'm considering purchasing Kingston HyperX 4GB . I believe it has 2000 Bus.and i have a gigabyte G41M-Combo which support DDR3 1333 . Will that work?
You haven't mentioned which part number. If it's KHX2000C9AD3K3/3GX this then from the datasheet (linked to PDF):
Translated: The memory should run fine, but the 2000MHz speeds are only under overclocked conditions.