Straight Dark lines on object and the render

Question

Straight Dark lines appeared after I choose Cycles as render engine and turn on denoising with Optix. Even I turned off denoising this is happening.

Even in the render, those lines appear. (Below is not a photo taken by a camera. it's a screenshot)

When I change the device to GPU from CPU. The final render has strange squares.

I am using Blender Version 2.93.4. My GPU is RTX 3060 6GB and drivers are up to date. Any ideas why this is happening? Thank you!

File - https://drive.google.com/file/d/1aVNyKiGdBhRH9C8GAOL7m9xuAb9iPeeT/view?usp=sharing

Answer 1

The problem comes from your light.Just reduce the power of your light and "strength" in World Properties will fix it.

Usually,the power of sun is high,kind of,maybe 2MW in blender.But the sun is far from us,so when the light attach the object,it will not has too much power.But,in your case,you choose area light,which we would like to set them around 1000W. Both area and point light is near,so the power should be much less than the sun.

You set area light to 2MW,trouble comes,too much light arrive your object.Even though they have bounced many times,their power is still stronger than 1000W or so.I guess the lines come from different bounces.

In graphics area,as far as I know,high power almost map to the same brightness value which near 1,so,although the light have bounced many times,2MW and 2000W looks quite alike,so the different lines on the apple looks the same,but I think they comes from different ways.