hey guys, wondering if anyone has any ideas about my mac pro early 2008 (2.8 ghz 8-core). i've got the standard 320 gb of hd space, 2 gb of ram, and the nvidia geforce 8800 gt every time i start up the machine (from power off), i hear the fans go on full blast for about 2-3 seconds and then they go quiet. does anyone else have this happen to them? also, during normal operation, i hear a constant "whirring" type sound - it fades in and out... is this normal? any ideas what's causing it? it's pretty loud... all i have open right now is safari and this is the sound it makes.... thanks!