Does GTX 750 support SLI?

Conclusion, this card is not made for sli as you can see the scaling is very bad with a software which scales any compatible multigpu to 100%. I never recommended, I only did it because I happened to have two of these. I have now dropped one of the GTX 750 Tis and got a 960 as my main because its a much better card.

Can GT 1030 SLI?

No, they can’t SLI. Lowest Nvidia card that can SLI is GTX 1070.

Can I SLI GT 730?

The GT series don’t support SLI. Also you need 2 pcie slots.