My GK45's 4k resolution is unusable. My 'monitor' is my Sony XBR-49X900F TV. I cannot stream any video without stuttering if I set the Windows 10 resolution to 3840x2160. I can stream 4k video directly to the TV (using the TV's apps) without any stuttering. Internet speed tests with my GK45 is 300 mbps. Has anyone been successful with 4k streaming or is the GK45 just too slow?