Cold Boot Attacks on Encryption Keys

Contrary to popular assumption, DRAMs used in most modern computers retain their contents for seconds to minutes after power is lost, even at operating temperatures and even if removed from a motherboard. Although DRAMs become less reliable when they are not refreshed, they are not immediately erased, and their contents persist sufficiently for malicious (or forensic) acquisition of usable full-system memory images.

Video
http://www.youtube.com/v/JDaicPIgn9U

http://citp.princeton.edu/memory/media/