[MSCE-VUE] How to avoid these artifacs in Ray Tracing mode?

Hi, 

what are the parameters to increase to avoid these artifacts in Ray Tracing mode?

I lazily tried to use "Interior Extreme" but they still stayed. I specify that the room is deliberately under-lit, there are only 2 Omni lights behind the camera and the walls are a bolean made from a single cube, so there are no cracks. Thanks.