the D865 chipset should have an AGP8x slot...
And AGP 8x should accept AGP8x and AGP4x cards, but NOT AGP2x unless it says so specifically in your motherboard manual. You probably don't have to worry about it since it would be almost impossible to find an AGP2x, and even the "newer" AGP4x cards, since all of them use the "newest" AGP8x. Talking exclusively about AGP of course, we've switched to PCIe now.