multi-in-ones are never 100% accurate when it comes to the emulation. hell some of them are barely 50%. you aren't going to get an accurate emulation of the game with those boards, there is just no way.
that said, it might be an issue with your video cable or board. if you can, switch out the video cable and see if it improves. if not, and you just bought your multi-in-one board, inform your seller and let them know it may be defective.
most monitors don't deal with the multi-in-one resolution signals. often you have to manually move/stretch/adjust the image to be center on the screen. the autoadjust usually doesn't fix it properly, you have to manually go into the settings on the monitor and change them.