A network administrator is upgrading a financial data server that currently contains two DDR4 unbuffered ECC (ECC UDIMM) modules installed in memory slots A1 and B1. To expand system capacity to , two additional DDR4 registered ECC (RDIMM) modules with matching clock speed () and operating voltage () are inserted into slots A2 and B2. Upon powering on, the system fails to Power-On Self-Test (POST) and emits a memory initialization error beep code. Which of the following is the primary cause of this system failure?
- Unbuffered memory (UDIMM) and registered memory (RDIMM) technologies are fundamentally incompatible and cannot be mixed within the same system.Cevap
- BPopulating slots A2 and B2 creates an asymmetrical channel population that disables dual-channel mode and halts POST execution.
- CExpanding system memory to four populated slots requires small outline DIMM (SO-DIMM) modules to comply with motherboard power rail limits.
- DThe operating system corrupted its bootloader configuration because the memory beep code indicates a missing storage driver.
Cevap
Unbuffered (UDIMM) and registered (RDIMM) memory modules cannot be mixed within the same system.
Unbuffered RAM (UDIMM) and Registered RAM (RDIMM) have different electrical signaling characteristics. RDIMMs incorporate an onboard register chip to buffer control and address signals between the memory modules and the memory controller, reducing electrical load on the host bus. UDIMMs lack this register and communicate directly with the memory controller. Because the memory controller cannot simultaneously adjust its signaling timing and electrical parameters for both buffered and unbuffered modules, mixing UDIMM and RDIMM results in a failed POST routine.
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RAM Types and Compatibility (UDIMM vs. RDIMM Mixing Restrictions)