How to get memory bandwidth from memory clock/memory speed

Question

FYI, Here are the specs I got from Nvidia

http://www.geforce.com/hardware/desktop-gpus/geforce-gtx-680/specifications

http://www.geforce.com/hardware/desktop

Answer 1

I think the correct calculation is explained here:
https://www.goldfries.com/computing/gddr3-vs-gddr5-graphic-card-comparison-see-the-difference-with-the-amd-radeon-hd-7750/

In short:
"(Memory clock x Bus Width / 8) * GDDR type multiplier = Bandwidth in GB/s

GDDR type multiplier is 2 for GDDR3, 4 for GDDR5."

There are many more details there, quite well explained and detailed.