Which Vizio 4K tv? I have the 60" P602ui-B3. Not sure I have tried any resolutions other then 1920x1080 and 3840x2160. Also runs at 640x480 (doesn't quite fill the screen top to bottom, but it looks right) and 1280x720
I'm guessing you are trying the HDMI output. It looks like the HD 5830 cannot display more than 1920x1200 on HDMI. However, DVI-D (Dual-Link) or DisplayPort can do 2560x1600.
Oh ok thank you, is possible DVI or DisplayPort to HDMI cable?
If there is a cable/adapter for that then yes, but it'll have to be DVI-D (Dual Link) or DisplayPort to HDMI cable/adapter. DVI-D (Single Link) will not work.
If you're going for the adapter then make sure the HDMI cable you will be using can support higher resolutions than 1920x1080.