Hmm, my YS isn't that loud (on a FOP32), but the damn thing vibrates.
Then again, with a tall heatsink, fan stuck on top and tiny contact area it has plenty of leverage.
Anyway, took a piece of pipe wrap (high density foam tubing, split down one side to slip over a pipe, any hardware store) cut a section about 2mm longer than the distance from the fan to my Radeon, cut it in half and wedged it in. Only a couple ounces of pressure on the video card, minimal contact area so it's not building much heat (like a Radeon's hot anyway), but it killed the vibration. No more low rumbling, never noticed much high pitched, but might help with that too.
Should work with any HS/F unit btw, worth a shot for anyone looking to try to cut a little vibration/noise out for a buck's worth of materials.
--Mc