The slider is showing a different image than what shows on the “Sample” page.
The slider featured image currently links to this – http://testmonkey.info/wp-content/uploads/green-marble-700×250.jpg
While the portfolio links to this – http://testmonkey.info/wp-content/uploads/green-marble.jpg
The default width for the slider is 732px, try adding that to the width in your slider settings, and then add the correct height that matches your image (which appears to be 321px). After you change the size, make sure to Regenerate your thumbnails as mentioned earlier and it should adjust the image from being cutoff , to actually showing the full image.