HDMI-VGA conversion may post compatibility problems under the following conditions * The HDMI source has different refresh rate than the VGA display * The VGA display (projector, monitor or TV) does NOT support the resolutions as output from the HDMI source (480i/480p/576i/576p/800x600/720i/720p/1280x1024/1600x1200/1080i/1080p) * The VGA display does NOT support interlaced resolution while the HDMI source is set to 1080i, 720i, 576i or 480i * The HDMI output of source device does NOT supply 5V/500mA power * For Macbook Pro with Retina, use extension mode. Do NOT enable 'Mirror Display'. In the meantime, set the resolution for external display to 1080p