I recently picked up the new Dell UP2715K absolutely beautiful 4K monitor, I have however just encountered a problem specifically when using Photoshop mainly when doing skin retouching work with brushes. When I move the brush or cursor during Photoshop I get black box instead of the cursor and sometimes black lines on the screen. The machine does become slightly laggy also. These are the specs i'm running on so not an old machine, I also want to add i'm not trying to use the Dell Monitor at 4K either, I was at 2880px wide I think. Any help would be awesome.