Dell Precision T5400 User's Guide - Page 126

Light Pattern Problem Description No memory modules are detected. Suggested Resolution 1 Reseat the memory modules to ensure that your computer is successfully communicating with the memory (see "Memory" on page 187). 2 Restart the computer. 3 If the problem still exists, remove all the memory modules and install one memory module in memory module connector DIMM_1. 4 Restart the computer. A message appears stating that because your memory is not paired, the system will operate with reduced performance and reduced error-correction capability. 5 Press to boot to the operating system. 6 Run the Dell Diagnostics (see "Dell Diagnostics" on page 136). 7 If the memory module passes, shut down the computer (see "Turning Off Your Computer" on page 151), remove the memory module, and then repeat the process with the remaining memory modules until a memory error occurs during start-up or diagnostic testing. 126 Troubleshooting Tools