The Go Board supports VGA output. But you have to get it just right or it will not work:
With a 25MHz clock, the most you can drive is 640×480 at 60Hz. The 25MHz is close enough to the pixel clock of this mode (25.175MHz): http://tinyvga.com/vga-timing/640x480@60Hz
You have to make sure the red, green, and blue levels are at 0 during the horizontal and vertical syncs, or the display will be blank.