Hi all. I have the early 2008 mac pro, standard configuration. I run a 30" ACD and recently added a second monitor. Ever since then I have been hearing this faint whirring sound, as if something in the machine is starting/reving up and then whirring down. It's audible to me because I have my machine sitting on top of a pedestal desk right beside my table. Does running two monitors make something inside, maybe a fan, run wierd? Could it be the fan of the video card? I am just curious, as I had not heard the sound before when I was running just one monitor. Oh, and the second monitor in question is a Wacom Cintiq. Video card is the stock ATI Radeon HD 2600 XT. I dare not open the side panel when the machine is running to check what's causing it lest I mess something up. It's like, rrrrrrrrrrrrr, rrrrrrr, rrrrrrrrrrr, like a miniature reving sound. LOL, that's the best I can do to imitate the sound. It's as audible as the sound of the regular fans.