W1700 uses a .47" DMD Chip to display true 4K UHD 3840x2160 (8.3 million pixels) with XPR technology of brilliant image performance, but it also causes inactive pixels which appear as a visible grey area. You can adjust the setup of the projector to eliminate the grey area and enjoy a full-screen projection by:
(1) Using a projection screen in 16:9 with 4-side black masking. Make sure the projected image is fully expanded to make full usage of the display screen.
(2) Projecting a 120”+ image
(3) Setting the lamp mode to “SmartEco”.
Please refer to BenQ website for more information.
https://www.benq.com/en/projector/cinehome-home-cinema/w1700.html