i have this 6950
http://www.msi.com/product/vga/R6950-2PM2D2GD5.html#?div=Specification
and will i be able to crossfire with a hd7770 @ pci express 3.0 or maybe even in pci express 2.0
http://www.msi.com/product/vga/R6950-2PM2D2GD5.html#?div=Specification
and will i be able to crossfire with a hd7770 @ pci express 3.0 or maybe even in pci express 2.0