I am using two computers networked. I was doing some tests in an attempt to separate the sound between the two computers so I can utilize a headset when I heard a horrible grating noise coming from one of the computers. I've heard the sound before so knew what it was; one of the fans was either failing or required lubricant in the bearing. A little odd considering both computer are less than 3 months old.
Variable Fan Switch
The computer has a variable fan switch on the rear toward the power cord. I lent down behind the MIP to either turn the switch to low or off in the hope of isolating the fan noise. As I selected the switch I heard "BLIP" and the computer stopped. I closed the other computer down, found a torch (flashlight) and peered behind the computer console. I saw the switch, but to my horror I also saw another switch. Sliding the computer out from behind the MIP I authenticated what I had thought. Instead of switching the variable fan switch I has tripped the switch that changes the computer from 240 volt to 110 volt. Both switches reside almost side by side.
Never change a voltage switch on the rear of the a computer from your countries voltage requirement. Depending upon which direction you move the switch and what voltage you are current on, will indicate the resultant effect. 240 V - 110 V "blip"! 110 V to 240 V "BANG" with everything "fried" beyond repair.
In some respects I was lucky, I only "fried" my power source. A replacement was relatively easy and I had a IT friend check the computer to ensure there were no other issues. Oh - and the noisy fan was isolated and replaced. It was the fan on one of the video cards (there are three video cards. The video card was replaced under warranty.
Advice For The Future
Use a piece of tape to cover the switch so it cannot be inadvertently tripped.