I have a 3090 RTX Card with 24GB of memory. I have a scene with a head with displacement and hair. It crashes when I try to render the scene. But the VRAM memory is not full: I also have an other Arnold problem. In render view (Interactive) the scene keeps rerendering in an endless loop (starting over every few seconds…
I did pre-populate cache. The first problem is resolved It was caused by a displacement setting. But the second problem I do not understand. In Interactive Arnold 'Renderview' it keeps re-rendering every 2 seconds from scratch instead of refining (CPU&GPU).
I assume you are on the latest GPU drivers? And you have done the pre-populate? Its under Arnold --> Utilities --> pre-populate GPU cache. And i see you use a non supported material? If you use displacement try to use less subD steps. Just as a test.
Do a info lig like i mentioned above. Than you get the info what Arnold is doing. Ornatrix could be an issue. But i fear you have to talk to the Ornatrix defs. In any case you should post your findings on the official support forum. https://answers.arnoldrenderer.com/index.html