During a scheduled upgrade of a rack-mounted virtualization host, a systems administrator replaces one of four 16 GB DDR4-2666 ECC LRDIMMs with an otherwise identical 16 GB DDR4-2666 ECC RDIMM because no matching spare is available. After the change, the server halts during POST and continuously emits a memory-error beep code. Reseating the new module has no effect, but removing it restores normal operation. According to standard troubleshooting methodology, which of the following is the MOST probable cause of the POST failure?
The CMOS battery has lost the stored memory-timing configuration.
The CPUs exceeded their thermal design limits after the memory change.
The power supply cannot provide the additional current required by the new DIMM.
The replacement DIMM type is incompatible with the modules already installed in the server.
Mixing different DIMM technologies (RDIMM and LRDIMM) in the same system is not supported on modern server platforms. Vendor documentation states that if these module types are installed together, the memory controller disables the affected channels or aborts POST entirely, which produces memory beep codes or error LEDs. Because removing the RDIMM returns the server to its original, supported configuration and restores normal operation, component incompatibility-not battery failure, thermal issues, or power-supply limits-is the root cause.
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What is the difference between RDIMM and LRDIMM?
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