Put simply, the GPU helps display the rendered layout onto the viewport or the UI. However, when 3D modeling is concerned, GPU plays a pivotal role, especially via GPU hardware acceleration. Besides, if you are using a third-party renderer like V-Ray with the preferred software or BIM tool like Revit, GPU accelerated rendering eases proceedings for the CPU.The VRAM, however, helps display the rendering and wireframe modeling results. Therefore, a higher chunk of video RAM automatically translates into lag-free visualizations.