I have a MacPro 3,1 (Mfg Sept 2008) which I have used from 18 to 20 hours a day since it was new. A month ago it started having noisy intake fan issues (the dual fans at the front of the computer). At first I thought it was a harddrive issue, but after replacing all my harddrives with Intel Sata 3 SSDs (Speed Demon 520s, which make NO NOISE at all) I realized it was Fan Noise (sounded like they were out of balance during a cold boot).
Well, to make a long story short, the problem appears to have been a nearly dead CR2032 battery. At least the problem has not reoccurred or recurred again since replacing the 3 1/2 year old lithiums. It is at least worth a try if your battery is several years old.
+
+
== Update ==
+
+
Fan Noisy and sounds wobbly prior to the boot "Chime" (Bong) then it smoothes out.
+
+
Discovered that my APC UPS backup power supply was defective and not generating smooth sine wave and/OR it was distorting the sine wave AC being fed to the computer.
POSSIBLE SOLUTION:
I have a MacPro 3,1 (Mfg Sept 2008) which I have used from 18 to 20 hours a day since it was new. A month ago it started having noisy intake fan issues (the dual fans at the front of the computer). At first I thought it was a harddrive issue, but after replacing all my harddrives with Intel Sata 3 SSDs (Speed Demon 520s, which make NO NOISE at all) I realized it was Fan Noise (sounded like they were out of balance during a cold boot).
Well, to make a long story short, the problem appears to have been a nearly dead CR2032 battery. At least the problem has not reoccurred or recurred again since replacing the 3 1/2 year old lithiums. It is at least worth a try if your battery is several years old.