Verified answer

with nvidia cards you cannot, however, with ATI cards, i believe the 4800 series can crossfire with each other, so you can crossfire 4850 with 4890 i believe.. but the older versions of ATI cards cannot do that, you have to match it exactly, same with all nvidia cards.

properly depending on what mom board you have, some enable this option yet there are basically some on the marketplace that permit this. because it rather is been performed in the past, you may the two completely harm your enjoying cards, get carry of an blunders message or your laptop won't initiate thoroughly till it rather is indifferent.