mac pro fan speed

Hello. I've brought my 2010 Mac Pro (purchased new in 2012) to my local apple store twice now. The last time they kept my computer for over a week running tests, wiping my hard drive, and replacing 2 fans in the enclosure. My Mac Pro still has a fan that revs up to maximum speed almost every time I use it, even when I'm not running any cpu intensive programs, and my temps are all low. I have no idea why this keeps happening. I've reinstalled the OS (so did the Apple Store), reset PRAM and SMC, uninstalled software that might have been the issue, and tested my ram. Nothing is keeping this from happening. It revs up to maximum rpm. I'm a composer, and this fan noise prohibits me from working on my music due to the loud fan (which actually emits an F# tone).

I don't know what else I can do besides ask for a brand new Mac Pro. I'm not bringing it to the Apple Store again because they haven't helped.

I'm running Mac OSX 10.7.4

2 x 2.66 GHz 6-Core Intel Xeon

32 Gigs ram

One 3 TB Western Digital HDD

One 128 GB OWC SSD, Two 480 GB OWC SSD

Anyone have a solution to this, besides having to get a new Mac Pro sent to me? Again, it was last at the Genius Bar less than a month ago, and after a week of testing and replacing parts, the problem persists. Thanks for your time.