Slow render with 1070+Titan than Titan alone - Why?

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1

I am running the newest version of Blender, official build, which says it supports 1070 cards.

I am running Titan and 1070 together, but I notice 2 wierd issues:

  1. Rendering the scene with Titan alone is faster than if I tell Blender to use both cards. It is as if the tiles left for the 1070 renders slower, and Titan is not helping my 1070 rendering the final tiles. Instead, it just waits for the 1070 to finish off (1070 is slower than Titan). It would be nice if instead of rendering tiles seperately, they could help each other with each tile. How do I achieve this in Blender/Cycles?

  2. When a tile is rendered on 1070 it does not tell me the samples-progress, like say I have 200 samples I want to be rendered, with Titan, Blender tells me exactly how many samples it has rendered so far. Why does Blender not tell me the same with 1070? Why is it hiding that information from me?

2

I’d especially appreciate an answer to my second question. Thank you in advance.