I maybe crazy but with R9 290s so cheap right now the idea of picking up another one is pretty tempting. My only issue really is likely the fact my mother board is PCIe 2.0 (scouring the internet sounds as if it isn't as big of a deal) with also only x16/x4 mode for Crossfire. My question is then would this be enough to not see a horrendous drop in performance, i.e. greater than 10%?.
Also the CPU at the helm would be a Phenom 2 1090t at 4.0 GHz (can't get it any higher sucks). Also for reference my MB is an ASUS M5A97 EVO AM3+ board.
Another relevant piece of information is the resolution I play at is only a single 1080p monitor so I am not pushing loads of bandwidth with crazy resolutions.