Overwriting free RAM space
Although it is considered that RAM is volatile (i.e., contents are erased with loss of electrical power), data remanence has been observed in it. In the studies, data retention in RAM was sometimes observed within seconds to minutes even at room temperature and a full week without refresh when cooled with liquid nitrogen. These data can be recovered by using a cold boot attack (platform reset attack).
Overwriting free RAM helps you to protect against memory recovery such as cold boot attack, which relies on the data remanence property of RAM.
During this operation, in addition to free RAM space overwriting, free swap files space also will be overwritten.
Currently, overwriting free RAM efficiently works on 32-bit operating systems and 64-bit with no more than 4GB of RAM. On 64-bit systems with RAM greater than 4GB, the efficiency is reduced - the more RAM, the less the effect.
On some computers during the process of overwriting free RAM space the system can stop responding to user actions for a short time (usually less than a minute).