It's no louder than a Mac Pro at idle. The fans are not variable speed. I have been using mine for about a year.
In fact, I'm about to go mobile and need to sell it soon.
Got the Mercury Elite Pro today... and I'm sad. It IS noisier than I'd hoped, but it's not that bad. Looks gorgeous, though, and extremely well-built.
On the same order, I also bought a Elite Pro Dual Mini. This one, I am in love with. It uses 2.5" laptop drives, has no power adapter OR fan, and, of course, is smaller.
So I will be selling the bigger Elite Pro with 2x 1TB drives sometime after Christmas and buying another Dual Mini with 2x 1TB 2.5" drives.
OWC has excellent customer service and will probably let you do an exchange.
That's strange. Mine is just as quite as the Mac Pro. Are you talking about fan noise or hard drive noise?