GTX 660/650-Ti in SLI or a single HD7970-Ghz Edition?

[xibalban]

The costs for either of the two configurations (see thread title) works out the same. Which one would perform better doing the following tasks:

■ Gaming
■ AutoCAD
■ Home Designer, 3D Simulations
■ Graphics Processing
■ Circuit Simulations/MathLAB

The core is i5-3570K.

 

[genrldisaray]

The 7970 is the way to go for all of those.