It appears that the disk encryption schemes used by different operating systems can be easily circumvented. Princeton Researchers have disproved a common misconception of one of the key components of a computer, that the system’s RAM loses all information stored on it as soon as power is cut from the chip. The researchers claim that the contents of the memory remain for seconds after the power is cut, and if cooled to low temperatures that that time can be extended to hours.
Princeton computer science professor Edward W. Felten, states that by using an inverted can of compressed air, a common item in most offices, you can effectively freeze the data on the chip for 10 minutes. In contrast using liquid nitrogen, not so common item in the office unless it’s a cryogenics office, the time can be increased to hours. Then the ram can be used cold boot the machine and the encryption key is still on the memory and can be used to access the encrypted disc contents.
Source: Information Week