The tool used for testing and stress-testing RAM is Memtest86+. Memtest86+ detects defects and errors by attempting to verify that the RAM accepts and correctly retains arbitrary patterns of data. In addition it attempts to detect errors in memory addressing, individual memory bits, and other memory anomalies.
Memtest86+ can be launched via the Hardware Detection Tool. While in the Hardware Detection Tool, Memtest86+ utility can be launched by selecting Memory from the Main Menu followed by Run Test from the Memory menu.
Memtest86+ Memory Diagnostic Tool
Detailed information about the Memtest86+ utility can be found at www.memtest.org.