Knowledge is never causative, whereas power always is. Power requires knowledge as part of it, but knowledge doesn't require power as part of it. God can choose to withhold or restrain His power, but He can't withhold or restrain His complete knowledge of things. They are separate attributes.

Wouldn't omniscience be included within omnipotence? If something has the power to do anything, doesn't that necessarily include the power to have knowledge of everything? Or conversely, I could say that total knowledge of everything includes the knowledge of how to effect the world in such a way as to bring about any event, i.e. the knowledge of how to be all-powerful. All-powerful and all-knowing just sound like the same property to me. So why do you monotheists usually treat them like they're two separate things?