How Many R9 290x should i get for 5760x1080 gaming and pcie 2.0 potential conflicts or bottlenecking

[WarHeaven]

mobo: ga-990-fxaud5
Proc : amd 8350 @4.0Ghz
Ram : Corsair Vengeance 2x4gb @1866 will soon be 4x4gb
psu : ocz gold 1250 watt

now i would like to buy a R9 290x gpu and would be nice to have 2 for crossfire but is it really necessary? @5670x1080 the extra horsepower would be nice and the memory bandwidth, shame the ddr5 didnt scale but do i really need it to max our setting while multimonitoring?

also my mobo has pcie 2.0x16 slots and i cannot anywhere find any benchmarks regarding the performance between pcie3.0 and pcie 2.0 especially with the cross fire bridge running thru the pcie slot that to me sounds like a performance hit even at x16 lanes and would really like to know regardless if i'm going to buy 1 or 2 cards, I MAY still buy another 1 in the future if i do no buy 2 now

 

[Zuul]

the difference between 2.0 and 3.0 PCIe crossfire is minimal talking about a few fps. You really couldn't see it as bottlenecking ... the amount of money it costs to upgrade compared to the miniscul loss of fps is just not worth it. crossfire in 2.0 should be fine! and 1 r9 290x is enough however if you would like more fps you can always get a second one if you have the cash for it but crossfire is known to have more issues than SLI I really would stick with a single card

 

[WarHeaven]

Its not that im worried about xfire and the small fps hit in pcie2.0 its the xfire on the r9 290x bridge running thru the pcie that worries me,
I will definitely try 1 card im upgrading from 2 560ti and mid high setting and no anti aliasing I with 3 monitors, I would like to max out setting eye candy all in most games with 5760x1080 resolution