One think to keep in mind is that in general, small U form factor cases are noisy, thanks to several tiny fans scattered all over the case, and most systems not spinning them down and up as needed.

To give you an idea, the 1U dual Xeon Proliant DL360 G3 is actually noiser then the 7U 8 processor Xeon Proliant DL760 G2.

Another thing to ensure is that when bolting it to the desk, make sure there are some rubber spacers to help prevent case vibrations from using the desk as a speaker.