My Mac Pro is about 2 months old. About 1 month ago I started to hear a vibration noise that emanates from the front grill. If I leave the machine going long enough eventually the noise disappears. When the noise begins I can stop it by either slightly lifting the machine from the front top grip, or just pushing in on the grill between the two dvd slots, toward the left side. I'm not really sure but I believe that this might have started when I installed the SSD with the IcyDock into bay 1 and moved the WD 1TB into Bay 2. I also installed a WD 2TB into Bay 3. I have switched the 2 WD disks around between various Bays, but have left the SSD in the IcyDock in Bay 1 because I was told that it might be important for the OS disk to be in the 1st Bay. Perhaps the weight of the other two disks are having an effect, or the fact that the SSD is so light in Bay 1 that the vibration started because of that. Or perhaps I just have to live with this. It does come and go so I suppose it can't be just because the SSD is so light. (I have pulled the SSD out of the Bay 1 and then re-inserted it just to be sure that it was firmly in place.) The vibration seems to be coming from the front grill toward the top. The machine thus far works fine and is relatively quiet so I don't want to fiddle too much with it. I know from an earlier thread that this has happened to a few others on the forum. Any further tips or explanations always appreciated.