I've noticed some people reporting that when using the HDMI cable, their text looks fuzzy, but with the DVI cable, it was crisp. However when watching HDTV signals on the monitor with the HDMI cable, everything looked good.
I've noticed the same thing myself on a second monitor.
I don't think this is due to a bad connection, but how some monitor's hardware deals with having the HDMI port used, and trying to optimize performance.
However, I have no proof, other than my own experience with text looking crappy from HDMI video output to HDMI monitor input, but fine from HDMI video output to HDMI>DVI adapter to DVI monitor input.