Look on the manufacturer website, and buy a card that is "approved" and tested for that motherboard, specifically. This will help you avoid problems. The manufacturer has a LIST of approved video cards, and memory sticks.
For how long do you think will I still be able to play high-end games with the hd7850? Will it be worth it to spend money on this card now or should I wait awhile for the new HD models to come out and then buy a 7870 or better for a lower price.