This is a common misconception. There is no difference in screen fidleity between a 72 dpi 4000 x 4000 image and a 300 dip 4000 v 4000 images. The dpi is just for printing purposes. A 4000 x 4000 at 72 dpi image would equate to a printing size of 55.5" x 55.5". A 4000 x 4000 image at 300 dpi would print at 13.33" x 13.33". Just figure out what size you're going to need and for what purpose. For high quality magazine work, 300 dpi is the standard. So if you needed a 5" x 5" picture, you would need a graphics render resolution of 1500 pixels x 1500 pixels.