Basically, the ROPs are in charge of the final stage of rendering a frame.

They do varying kinds of postprocessing on the almost final stage of a rendered frame, and then push the finalized pixels to the frame buffer.

A rough analogy would that ROPs are in charge of the final editing pass on a paper or article before its published, with the analagous ‘research’, ‘fact verifying’, and ‘rough draft’ having already been done by other parts of the GPU first.

Maybe another analogy would be that ROPs are the ‘final assembly’ of a frame, if constructing a frame was like building a car or aircraft.

A simpler, more literal explanation is that the ROPs perform the final stage of rendering a frame before the GPU actually pushes it out for you to see.

So… if the GPU is missing 8 ROPs… the GPU is basically bottlenecking itself, internally.