The problems with the viability of the concept of omnipotence are wll known; those of omniscience, not so much. This goes so far as to concern us with the
definitions of these concepts. Neither of these are very well defined concepts, to be honest.
Given certain of these definitions, however, it's easy enough to demonstrate that such a God doesn't exist. For example, God's knowing the future would seem to contradict his omnipotence (he cannot change such a future, etc.)
There is one such treatment
here. And
another, with quotes showing that the Bible can be used to refute the idea that the Christian God is a God of the "omnis".