2010 Mac Pro 2.8Ghz Quad fans running at high rpm

My (mid 2010) 2.8Ghz Quad core Mac Pro (5,1) fans are running full blast. No processes are happening up front or in the background according to Activity Monitor, and it's unerving to hear the speed and force of the fan (I think it's the front fan - intake).

Sometime ago, a year maybe, I had issues with my Mac Pro bluetooth not showing up, it didn't exist in my System Prefereces! It shipped with Bluetooth and sometimes it showed up and my wireless keyboard and mouse worked, but sometimes it not only didn't work, but literally was not listed under System Prefereces. That issue became such a problem that after communicating with Apple Support, they eventually replaced my entire motherboard.

Since then everything has worked perfectly until last night when I rebooted after a 24 hour period of rendering a project in After Effects. The render was complete and the Mac Pro sounded normal, but I decided to reboot. When it came back on it sounded normal for a few seconds and the front intake fan began spinning up until it was running at full rpms and now it runs full always. I tried a SMC reset, and tried the sleep / wake process but nothing stops the full-tilt intake fan issue.

I am not sure it is hurting anything but it is so loud and disturbing that I don't feel confortable running it. I've been working with Mac Pro's forever - and at work we have two, and older 3Ghz dual quad, and a new 2.66Ghz dual 6-core, and I've never had any issues with them. Before those I've used a hand full of older Mac Pro's but that's going back a long time ago.

I don't know if my coverage started over when I had the motherboard replaced - it was basically a new Mac Pro and I even recieved a new SN. I was kinda shocked at the solution because to me, the issue was the bluetooth card, so replacing the entire motherboard just seemed crazy. I felt like the nightmare Apple customer.

Do any of you have some advice about Mac Pro fans spinning at full speed???