Even with their sturdy construction and usefulness, DIMM slots occasionally pose problems that could impair system stability or performance. The memory modules not being seated correctly in their slots is one frequent problem. System instability or boot failuresrammuy may result from a partially inserted DIMM or a slightly misaligned DIMM. It's best to fully shut down the computer in order to diagnose this problem, then carefully reinstall each module, making sure that it clicks firmly into its designated slot. Incompatibilities between various RAM types or differences in speed between installed modules are another common issue. For example, your system may not boot up or may perform at a lower level if you combine RAM modules with different clock speeds or mix DDR3 and DDR4 RAM.