MacBook Pro early 2011: sound loop, black screen
It is a case of desecrete GPU failure. Most of the Early and Late 2011 MBP are prone to this failure. The culprit is the AMD GPU. See more at the links below.

http://www.digitaltrends.com/computing/suddenly-bunch-early-2011-macbook-pro-owners-running-video-problems/

http://www.cultofmac.com/262861/early-2011-macbook-pros-dropping-like-flies-heat-issues-blame/