It's my first message on the forum and i'm sorry to begin with a problem !
I just changed my graphic cards and the new ones are not recognized.
I upgraded to version 3.0 a few days ago and it was working just fine with one Geforce 970. Yesterday i added 2 Geforce 1080. During my first render with all GPUs, only the 970 seemed to work and there was no improvement on render speed. Octane was using 4G on VRAM, ignoring the 2 GTX 1080.
I decided to make a test without the old 970 graphic card and removed it from the computer.
This time, with only the 2x1080 graphic cards, i have this message (it didn't appeared before since the GTX 970 was recognized) :

The driver is up to date and installed yesterday. Both graphic cards are recognized by the system, but not by Octane.

By default, both cards are unchecked in the settings. Even if i check it, it doesn't change anything and the same message appears.

I tried to check all boxes and enable "USE ALL GPUs" in Cinema4D but i still have the same message.

I would prefer to use Octane plugin for Cinema4D since i'm not very comfortable with Standalone but i tried to install it and give it a try and see if the cards were recognized. It seems that the problem is the same !

I believed it was a straightforward procedure but i guess it's not. Could someone guide me and tell me if i forgot something or did something wrong ?
I'm very much looking forward to see those card in action, combined with Octane ! (the GTX 970 alone was quite fast already !)
Thank you very much to all !