Well keep in mind memory bandwidth & "bit" acs.
My testing of 2x7950 cf yeild on average 3.4 (yellow) with the odd 6.0 barely green.
Dual card memory acs 764bit single 384bit. So bandwidth can help alot. In Game debate the cf 7950 comes up comparable with 1 r9 290 4gig.
Single 7950 complete no go.(which is disapointing considering xb1 & ps4 gpu equivilent is less but has more memory available)
Now with the cf setup a bit of ghosting in both in 1.2.x in 1.1.92 more friendly with older hardware.
Now running in my other rig a single r9 390 which scores green 7.4