I had the same issue with running xbox to the pg279q and that has HDMI input.
I needed to change the xbox to 720p resolution
changed the settings for color to RGB I think
and changed the color depth to 24-bit
That's what worked for me I think. After it was working I tried a few different settings and it seemed that if any of those settings were not what I posted it did not work. the Image was playable but since it was 720p being put into 1440p worth of pixels is looked a little "fuzzy".
heres the page explaining each option
http://support.xbox.com/en-US/xbox-one/console/adjust-display-settingsAlso I'm not sure why this was resurrected from more than two years ago.
I7-4790k OC 4.9 1.375v
MSI Gaming X GTX 1080 OC core:2055Mhz Mem:5504Mhz
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