7870 Xfire effectiveness

Build:

Case: CM Storm Stryker
MB: GIGABYTE|GA-Z77X-UD5H Z77 http://www.newegg.com/Product/Product.aspx?Item=N82E168...
CPU: i5 3570k
Cooler: CM V8 (may not be the best but I do love the look of it and won't overclock like crazy anyways)
HDD1: WD 1 TB Blue 7200 RPM
HDD2: Intel 335 240 GB SSD http://www.newegg.com/Product/Product.aspx?Item=N82E168...
MEM: 16 GB (4x4) G.Skill 1600 http://www.newegg.com/Product/Product.aspx?Item=N82E168...
GPU: Gigabyte 7870 OC http://www.newegg.com/Product/Product.aspx?Item=N82E168...
PSU: Corsair HZ 750W Gold http://www.newegg.com/Product/Product.aspx?Item=N82E168...

The rig will be used entirely for gaming and browsing, no video or picture editing of any kind. Play most of the popular FPS, Black Ops II, Planetside 2, also Skyrim, whatever is out I normally like to play. Although I would appreciate comments on the build in general (although I should mention that the SSD was on special down to $169 before anyone comments on why I chose that one), I am really curious about the advantage of adding a second 7870. I really struggled to find benchmarks with 12.11 drivers that show the performance of xfiring these cards vs a more powerful single gpu.

I know the normal suggestion is to go with the single card so you can really upgrade down the road, but I just don't see myself ever needing to xfire two 7970's, as an example, when I game on a single 1080p monitor.

FYI this is my first post and any suggestions on how to post in the future to make your job easier would also be very welcome.


Kind regards,

Mike