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Difficulty: HardMotherboard, RAM, CPU, and Power Issues

A systems technician is diagnosing an enterprise desktop workstation that fails to complete POST. The motherboard status LEDs halt consistently at the DRAM indicator. The system is equipped with two identical 16 GB memory modules. During diagnostic isolation, the technician verifies that both memory modules function correctly and boot when tested individually in slot A2. However, whenever any memory module is installed into slot B2—either individually or paired with slot A2—the system immediately fails POST at the DRAM indicator. Which of the following is the most likely root cause of this failure?

  1. Bent CPU socket pins or damaged motherboard circuit traces connecting to memory Channel B.Answer
  2. B
    A corrupted operating system boot loader preventing dual-channel memory driver initialization.
  3. C
    Memory modules installed into adjacent motherboard slots disabling single-channel fallback support.
  4. D
    Full-sized DIMM memory modules mistakenly installed into a laptop motherboard SO-DIMM slot.

Answer

Bent CPU socket pins or damaged motherboard circuit traces connecting to memory Channel B.
Because both memory modules passed POST when tested individually in slot A2, the memory sticks themselves are fully functional. The POST DRAM halt occurring specifically when slot B2 is populated isolates the issue to memory Channel B. Because modern CPUs integrate the memory controller directly on the die, bent CPU socket pins or cracked motherboard trace lines between the CPU socket and slot B2 disrupt electrical continuity, preventing Channel B from initializing during POST.

Step-by-Step Solution

1
Analyze diagnostic isolation results for the memory modules
Both memory modules successfully complete POST when installed individually in slot A2.
This confirms both RAM modules are known-good components and eliminates RAM stick failure as the root cause.
2
Isolate the failure domain based on slot behavior
The failure occurs exclusively when slot B2 is populated, stopping hardware initialization at the DRAM POST stage.
The symptom isolates the fault to the physical communication path of memory Channel B.
3
Identify the underlying hardware failure
Bent pins inside the CPU socket or fractured motherboard traces interrupt electrical continuity between the CPU integrated memory controller and DIMM slot B2.
The CPU memory controller communicates directly with DIMM slots through LGA/PGA pin contacts and motherboard trace lines. Physical damage along this pathway causes memory initialization failure during POST.

Key Concept

RAM Channel Isolation and Socket Pin Diagnostics
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Topics

Motherboard, RAM, CPU, and Power Issues

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