And if I responded to that, suggesting that is correct, you would immediately point out the example from the reduction paper, which you already pointed out.
I’m not going to go back and forth on this. Both are correct. There isn’t just one formula that applies to every case, for every situation. If you want to come up with one formula, I personally would do exactly what I already suggested. Create a formula that is based on transfers per second. Then for each situation you come across, see what relationship memory clock rate must have to transfers per second, in order to make that single equation correct.
The peak theoretical memory bandwidth of GTX 1080Ti is published:
You can decide for yourself what formula and memory clock rate you wish to use, to acknowledge the correctness of that published number.
I probably won’t be able to respond to further requests for clarification on this topic. The topic of what is the GPU memory bandwidth formula has been discussed in many places. If you want to read some of those, you may reach some conclusions that are useful for you.