GPU fan

I used to have a 550TI. Its fan curve was quite aggressive.

Default was about 1580RPM and at max load would get up around 2120RPM. Now by getting really loud do you mean you hear the fan speed up, and then the fan stops moving altogether? That would be bad.

If its not that, then you are just hearing the fan adjust to rising and lowering of temps. =D
 
I had a reference 550TI from HP and I had the same thing happen on my first one. It would just randomly get really fast and really loud even when I wasn't doing anything.
They replaced and said that it was probably a faulty fan controller. The 2nd one didn't have this issue.

Sound like what your having?
 


Just played diablo 3 and it wasn't getting loud and fast. Afterburner reported that the card wouldnt go over 80 degrees and averaged around 70-75 degrees. Fan speed was at 40-50.