I don't think I need to worry about this but basically the 2 HDDs in my new pc make a sweeping sound. If I put my hand on the side or in the front of the case u can feel a strong rotating vibration. they are 7200 rpm HDD 320 gb and 100 GBs HDD. I've have really had a problem with them I am using the NZXT phantom case. even with the rubber groumets built into the Hard drive sleds they still vibrate. besides when I only had my SSD in there was absolutely no vibrations.