First i want to say, great job on the data and the blog. I appreciate the anyone who takes the time to investigate and put in real time to try to analyze things themselves.
We have been discussing some of the potential reasons. For starters, Maxwell is structured differently than kepler and it breaks down different. Surely you have heard that maxwell is 128 cuda cores per SM and kepler was 192 per SMX. But for kepler, that is 192 cores per SMX- which all shared the same cache texture cache, unified cache, and L1 cache).
maxwell 128core SM is different in a pretty large way, the cache (L1,Texture) is shared between
two blocks of 64 cores. Also the L2 is much larger. It breaks down much more elegantly,
http://www.eteknix.com/nvidia-gtx-750-ti-2gb-maxwell-graphics-card-review/2/
http://devblogs.nvidia.com/parallel...ould-know-about-new-maxwell-gpu-architecture/
These differences show up from time to time, kepler can be at a disadvantage.
https://compubench.com/result.jsp
We also have AMD GCN in all the next gen consoles, this was supposed to give AMD GCN an advantage in PC as game engines are designed around that specific HW. There have been titles that kepler struggles on, I think maxwell is just better suited in those. And as more titles get built from the ground up, with the next gen consoles in mind, the issue wont go away.
If consoles ports start using direct/open compute, then kepler performance will suffer. We could call it a scheduling issue, kepler just being the odd one out.
There are plenty of engines that are still in use that kepler will still be fine in. And dont get me wrong, I am not saying that this is all that is going on here. AMD has also done a lot to improve their performance these past few years as well. The omega drive gave AMD GPUs about a 10% performance jump across the board. That is pretty awesome right there, I believe that nvidia has also improved Maxwell performance at least 5% or more since launch.
Maxwell is more different than most people seem to think. Its strengths are in the areas where kepler has been weak. So in the end, i think that there will be cases that maxwell and GCN both do well in. But it is not the end of the world, far from it.
People are trying to spin this into some huge conspiracy when there are very real and technical reasons right there in front of them. There is data showing kepler weaknesses all around and in these same areas, Maxwell does very very well.