A power supply can definitely assist in the squealing as it is the dirty power coming into components that causes it... the first 3 units there are all multiple rail PSU's with under 20A on each 12V. The Ultra X-3 is a single rail design but all ultra PSU's, while performing within spec, do not have particularily clean DC output. The X-3 in particular, when loaded lightly, as it would be in most systems, has rather dirty output:
248W
499W
While the board has something to do with it no doubt, the power supply it is paired with could make a huge difference, and is not so easily ruled out. With one PSU it may be intolerable and with another it could be just fine. ;)