You wish to know how Symantec Endpoint Encryption protects against the "Cold Boot" attack.
For current status on Cold Boot as it relates to both Symantec Endpoint Encryption 11 and Symantec Encryption Desktop 10, see article INFO5209.
The "Cold Boot" attack is a way to bypass software-based Full Disk Encryption (FDE) by using the basic characteristics of DRAM found in all PCs. A method to achieve this was published by Princeton University researchers in February 2008.
Cold Boot Attack 1