I also have a SmartUPS that has a very noisy fan and sometimes seems to vibrate/resonate. Mine's a model SMT1000, not a SUA model. The fan in this unit is made by ADDA and has the following specs: 80x80x25 mm, 24V (**yes, 24V**), 0.10 A, 2440 RPM, 31.4 CFM, 28.3 dB(A). I measured the noise as 45 dBSPL (1 ft to the side of the unit) when it was "vibrating" and 42.8 dBSPL running "normally".
I had hoped to reduce the noise by replacing the sleeved fan with a higher quality one but the fact that this one runs off a 24-Volt supply has made it hard to find a suitable replacement. Why APC would put such a cheap, noisy fan in such an expensive UPS is beyond me except that I guess they are targeting servers with this unit. I would not recommend anyone purchase the SMT1000 for use in any room where someone also worked or relaxed.