During a memory upgrade, a technician adds four 64 GB DDR4 load-reduced DIMMs (LRDIMMs) to a dual-socket rack server that already contains eight 32 GB DDR4 registered DIMMs (RDIMMs) operating at the same speed. When the server is powered on, it halts during POST with a fatal memory-initialization error and will not boot. According to common vendor memory-population rules, which corrective action will allow the server to start while letting the larger modules remain in service?
Replace all RDIMMs with LRDIMMs so every populated slot uses the same DIMM type and speed.
Install the LRDIMMs only in the channels assigned to CPU 0 and leave the RDIMMs in the channels for CPU 1.
Reduce the memory clock speed in BIOS to the lowest speed supported by both DIMM types.
Move the LRDIMMs to the priority (blue) slots and leave the RDIMMs in the secondary (black) slots within each channel.
Most server vendors state that RDIMMs and LRDIMMs are electrically incompatible and cannot coexist in the same system. Mixing the two types causes memory-training failures, so the system stops at POST. The fix is to use only one DIMM technology across all populated slots. Removing the existing RDIMMs and repopulating every channel exclusively with LRDIMMs of identical type and speed eliminates the incompatibility and allows the server to complete POST. Placing different DIMM types in separate CPUs or slots, lowering the clock speed, or changing slot order does not resolve the fundamental electrical mismatch, so those actions will not restore normal boot operation.
Ask Bash
Bash is our AI bot, trained to help you pass your exam. AI Generated Content may display inaccurate information, always double-check anything important.
Why can't RDIMMs and LRDIMMs be used together in the same server?
Open an interactive chat with Bash
What is POST, and why does it halt due to memory issues?
Open an interactive chat with Bash
What are common vendor memory-population rules for servers?