Now he want to know how cards in CF/SLI can work faster if it dosent stack together...
That's like saying a GT610m with 2GB of RAM would be the same speed as a GTX 680 with 2GB of RAM with his logic.
Does a Dual core CPU perform the same as a quad core just because the system still has 4GB of RAM?
Nope. It's because the System has more power to process the data. The RAM itself simply holds the data, for the processor (CPU or GPU) to do the workload.