First post on the forums, so if I do something wrong, let me know!
I've been experiencing a weird issue, dunno if it's something with my setup, or if it's a setting somewhere, but I've been experiencing a noise block on my renders, even after rendering loads of samples. Saving the image after rendering, still has the noise block. Here's a reference image:

Any idea why this is happening? Is this because of my different models of cards? Any help would be wonderful!
My setup is:
2 machines
Both are connected via ethernet to each other, and both render fine, except for these noise blocks I see in the render
1st: Windows 10 Pro
2x GTX 1080
32GB DDR4 Memory
Nvidia Driver version: 368.81
Octane Render Standalone Version: 3.03.2
Octane Render Plugin Version: 3.03.2-R1
Maxon Cinema 4D R17.048
2nd: Mac OS X 10.11
2x GTX 980
16GB DDR3 Memory
CUDA Driver Version: 7.5.29
Octane Render Standalone Version: 3.03.2
Octane Render Plugin Version: 3.03.2-R1
Maxon Cinema 4D R17.048