messing up my settings

Moogoo

So I thought my renders were going slow because I haven't rendered anything in a month, so I started messing with my settings but when I turn off the CPU marked with red arrows on my screenshot it tries to render but renders a blank screen in a split second which seems odd as I thought Iray was a GPU user.

So the questions-

Is the blank render normal with the same settings as in my screenshot but with the CPU unchecked?

My screenshot is my normal settings is that how it should be?

On the screenshot I did a green circle where it used to say how big the render is, has that gone?

Also computer start up times getting slower what is the main cause of this, temp files? pictures?

rrward

Did you update your video drivers after you updated to Studio 4.20?

Moogoo

no i will try that cheers