Firstly I want to tell you that I'm sorry for my grammar and my spelling, I promise to do my best

So.. like I said in the main title, I have a problem, a weird problem..
Let me explain :
I'm on a project with aproxymatly 1 000 000 triangles in my scene (you can check the make preview here : https://drive.google.com/file/d/0B5wraU ... ZJLVE/view ).
When i start the render (MAJ-R), octane load all this stuff and show me the render in the picture viewer (so far so good), but, sometimes he crashed after 1min30 (during the loading), sometimes he crashed during the render, sometimes at the end (during the save) and sometimes he render 3days long without any problem..
The crashs are différent, sometimes a c4d bugfil, sometimes a nvidia error (see attachement), sometimes black screen, sometimes my dual screen exploade (i'm on 1 screen on a fuc***g small résolution something like 800*600

It's actually impossible to do a frame without a crash and i still have much to do.
I can't find from where is the problem
Here are some more informations about software.
Windows 7
cinema 4d r16.038
Octane 2.22.2 Test3
asus p8z68 deluxe
i7 3800mhz
32 go RAM
1 gtx 680
1 gtx 980
(last update for my gtx are done)