I'm going to try my best to describe an issue that started up yesterday, after two years of wonderful performance, that I'm unsure of the cause. 

My primary fan (over the radiator for the liquid cooling system) on my alienware aurora has been cycling on to maximum rpm (slightly over 4000rpm) and won't cycle off. However, all of the sensors indicate that its running at a cool 23 degrees celsius or so. And, when I place my hand behind the system fan to feel the air being blown out, it is pretty darn cool, as in no indication of overheating.

So, I'm lead to believe that for some reason I can ascertain, my fan is peaking without cause. (A cause thats readily apparent.)

It's working so hard, its pulling all the power from my power supply. For awhile, the issue was manageable. Then my frame rates started crashing, because power was being shunted away from my gpu. Obviously, I freaked out and stopped doing *anything* system intensive. Fan still blows. Eventually, the cycles on became longer and longer to the point that once it comes on, it just doesn't go off. After I started up my system, I have about 7 minutes or so before the fan comes on and runs constantly. It's pulling so much power, my system is shutting itself down.

Tried dusting my computer interior. And while it was dusty, it did absolutely nothing towards fixing the problem.

As per an IT friend's suggestion, I tried to find fan settings in my BIOS, but didn't see any. (I'm relatively green when dealing with BIOS.) I noticed my BIOS version was old (A04) and tried installing A11, and upon restart from what I thought was a successful completion, it read that I was running... BIOS A04. And sure enough, everything seemed to be identical.

So if this is a BIOS issue, I seem to be rather helpless. Could this be the symptom of a failing fan? I would think it would stop working, rather than work way, way more than is necessary. 

I would like to reiterate for the sake of clarity that there is *no* overheating going on, and aside from the systems fan going absolutely crazy, I can't find anything else wrong with the PC.

Any advice/suggestions would be appreciated. I'd like to be informed before I start buying random parts and replacing, hoping to find the right one. (If it's even a hardware issue.)