New Patreon Tier and Early Access Content available. If you would like to support AVForums, we now have a new Patreon Tier which gives you access to selected news, reviews and articles before they are available to the public. Read more.
My gutshot is flaky graphics software. Try installing the latest GPU drivers and start again.
Less likely, some other program or app or game on your pc has thrown a switch somewhere, like refresh rate (should be kept at 60Hz I think or you might get PAL/NTSC issues).
Does the 607 have a VGA in you can try so you can narrow down the possibilities for supported video modes?