Here are a few benchmarks for the ZOTAK AMP! Extreme card. These were made using Octane Render 3.02 and the benchmark scene in Lightwave 3D rendered at 1280x720:

ASUS Titan X 12GB alone - 43 seconds
ZOTAK 1080 AMP! Extreme alone (also being used for monitor displays) - 41 seconds
ASUS Titan X 12GB ...

I just received two ZOTAC GeForce GTX 1080 AMP Extreme cards yesterday with the intention of replacing my dual Titan X cards. Unfortunately, I didn't realize that the Zotak AMP Extreme is so gigantic -almost 13 inches long. I can only fit one in my case. I'll have to ebay the other and replace it ...