I’ve got an AMD Pitcairn chipset graphics board here. Does 1080p nicely in Haiku. It’s a Gigabyte Radeon R9 270 board, PCI express 3.0 (backwards compatible with older PCIe slots, as they all should be if they followed the standard).
Got it from NCIX, an online + brick store (conveniently they have one in Ottawa Canada so shipping is easy for me - just order online and pick up there). http://www.ncix.com/