Try to hear my words, really hear it not just answer it.
I do this job for 20 years and today for the first time in 20 years i had to change my workflow in the middle of my production because octane V3 couldn't render high size any more.
So my advice, make otoy team strongly test updates before release, working with octane is just like playing lottery.
Anyway, i still crash with your settings.
I upload the file in attachment if you want to get an eye on it. (3dsmax 2018)
What driver do you use ?
Thanks