I have an HD5850 from about 3 years ago and recently I was a whore and upgrade from two 19 inch monitors to two 23 in monitors.I have start noticed some serious video lag during major scene changes when gaming (and running both monitors). I'm sure turning off one monitor would resolve the issue, but I'm suborn and I don't want to.
I was going to try to find a cheap card to run screen per monitor but I don't believe that is possible. I thought about trying to run crossfire the HD5800 and 5900 series have been discontinued and I think those are the only two cards I could pair together. I have seen used graphic cards for sale but that sounds risky - open to feedback on the subject though.
my MOBO supports PCI-e 2.0 and I was hoping to get away for under $200.
No it doesn't make sense to get 2 of the 7770 mainly because you get 1 gigabyte no matter what if you were to run crossfire in that configuration. The 7850 would be the best solution at the price point that you have laid out what manufacture is up to you. What does the rest of your system look like?
It's not all about what CPU you have. There aren't things within a CPU now to say you have a AMD platform were going to play nicer with you. Point is that around 200 dollars the best option you really have for you is the 7850 now if you were to say $250.00 you have other options you have the 660Ti which is almost in that bracket you have the 7870 but keep this in mind the 7850 is a mid level card you are going to see mid level performance with a 7870 as well its not until the 7950 that you are going to see higher performance.
The OP said he would like to spend 200 or less unless that changes the best option at the price point that he has laid out is the 7850. It's not even debatable there isn't a 200 dollar Nvidia card there is a 220 nvidia card the gtx 660 but its not 200