Try to keep your graphics card driver up to date: AFAIK, today Catalyst 9.3 will be released, so stay tune. If this won't help, try to install your monitor driver (maybe you'll need to download it from Internet). Then, if this won't help too, try to check your DVI connection - the problem could be in DVI connector of graphics card (so try other one), in DVI cable itself (do you have a firm one?), or even in graphic card! I'd like to suggest you to test your graphics card with another monitor, or (if it's possible) another graphics card with this monitor.