Here are the amd requirements for a 6950. 500w with 2 75w pcie 6 pin power connectors.http://www.amd.com/us/products/desktop/graphics/amd-radeon-hd-6000/hd-6950/Pages/amd-radeon-hd-6950-overview.aspx#3
I am not familiar with aero cool psu's.
It is a tier 4(not recommended) on this old list, so perhaps it will not deliver the 550w that the name implies.http://www.xtremesystems.org/forums/showthread.php?108088-Official-XS-Power-Supply-Ranking-Phase-I
In theory, it should be OK. But, a low quality psu under stress can destroy not only itself, but take other components with it.
I suggest you look for a Quality psu.
My short list would include Seasonic, Antec, Corsair, PC P&C, and XFX.