Dell Precision T7400 User's Guide - Page 111

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 172). 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 123). 7 If the memory module passes, shut down the computer (see "Turning Off Your Computer" on page 139), 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. Troubleshooting Tools 111