Graphic card support and CPU-GPU comparison

Dear Community,

on the Materials Studio Website is written:

"

Graphics Cards:

Materials Studio is designed to work  with all types of graphics cards. Performance and quality improvements  are generally observed when using the Nvidia Quadro® range of cards.  Limited support is provided for AMD or ATI graphics cards.

"

I would like to build a new PC and choose my Hardware (financially limited).

Would you recommend to buy a semiprofessional/ multimedia nVidia card, like the GTX 780?

Are those improvements (compared to pure CPU-calculations, i.e. i7 Quad-Core) limited to the Quadro Cards or could I expect better performance with a "normal" card, too?

Does anybody know if nVidia SLI is supported by Materials Studio.

Thank you.

Greetings.

Romans