My manager went out and bought a tesla K20 for me which arrived a few days ago. I have been testing lots of combinations of cards to see what we get including a newer pcie3 and an older pcie2 machine. The results aren’t too great sadly.
Below are some fo the results for a test scene consisting of multiple views in a static scene containing 150 lights in an acceleration structure rendering @ 1920x1200:
GPU | Max | Mean | Min
580 13.571 9.883 7.065
680 17.021 11.962 8.569
680 (580 video) 16.485 11.830 8.409 (Relative to card on its own: 1.0325, 1.01116, 1.0190)
K20 (580 video) 17.455 12.465 9.060
K20 theoretical 18.022 12.604 9.232 (Based relative performance of 680 when using 580 for output)
K20 vs 580 132.8 127.5 130.7
K20 vs 680 105.9 105.4 107.7
As you can see from the k20 vs 680 results there ends up being little to no benefit (for what we are doing at present) for using a K20 in ray-tracing. We would expect that possibly in the correct cases dynamic parallism may be used (maybe?) for the ray-tracer or when the test scenario gets more complex there could be many more benefits.
I should also mention on the PCIe2 setup we saw a ~140% relative performance. This is no where near the 145% better performance stated in the Design garage but I am not sure if you mean the figure is relative and infact 45% better performance?
p.s. As a side note anybody needing more memory should definitly take a look at these cards or a Quadro as they are immense in that sense!
EDIT: Appears tabs/spacing doesn’t get kept by the forums :(