The 912 will fit even larger last-gen cards. The center drive bay can be removed to accommodate the longer last gen cards even (up to 15.4") and still has bays for up to 2 SSDs and 3HDDs.
Are all your drives HDDs or do you have any SSDs?
If you have all HDDs?
If you have 4 HDDs, you'll want to keep the center bay in. This case can accommodate up to a 10.6" card ( http://www.coolermaster-usa.com/product.php?category_id=19&product_id=3009
). As long as the 6870 (9 7/8" long per http://www.youtube.com/watch?v=Mazv1EJQiuo
) you choose has the power connections on the side-panel side of the case (not toward the front), this case will be just fine. Most newer cards are setup this way.