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Difficulty: Very hardMotherboard, RAM, CPU, and Power Issues

A desktop technician is troubleshooting a custom liquid-cooled workstation that abruptly powers off during heavy multi-threaded CPU rendering tasks. Immediately attempting to restart the computer results in the fans spinning at maximum speed for two seconds before the system shuts off completely with no POST beep codes or video output. However, after waiting fifteen minutes, the system boots into the operating system normally. Upon inspecting the physical installation, the technician discovers that the plastic protective film was never removed from the liquid cooling block's copper base before mounting, and the primary EPS12V 8-pin CPU power cable connector is partially unseated from the motherboard header.

Which of the following directly explain the root causes of the observed system behaviors? (Select TWO.)

  1. The unremoved plastic film acts as a thermal insulator, triggering the CPU internal thermal protection circuit to force an immediate shutdown under load.Answer
  2. The partially unseated 8-pin EPS12V connector causes inadequate power delivery to the CPU VRMs, preventing stable POST initialization during high-current draw events.Answer
  3. C
    The system RAM modules are unbuffered SO-DIMM modules installed into standard DIMM slots, causing timing failures that clear after capacitors discharge.
  4. D
    The lack of POST beep codes indicates complete BIOS/UEFI firmware corruption caused by persistent operating system driver crashes.

Answer

The CPU thermal shutdown is caused by the insulated plastic film on the cooling block, while the POST failures and immediate power-offs stem from an improperly seated 8-pin EPS12V power cable.
The system experiences two concurrent physical hardware faults: an unremoved plastic protective barrier on the liquid cooling block prevents conduction, causing rapid thermal overload under workload; while a loose EPS12V 8-pin auxiliary CPU power cable starves the processor VRM circuits, causing sudden shutdown upon initial current draw.

Step-by-Step Solution

1
Analyze thermal symptoms and delayed successful booting.
The machine shuts down under high load and fails immediate reboot, but boots after cooling down for 15 minutes.
The plastic film prevents heat transfer from the CPU heat spreader to the cooler block, causing rapid overheating and triggering thermal trip protection. The 15-minute wait allows CPU temperature to fall back below critical thermal safety thresholds.
2
Analyze instant 2-second power-off and lack of POST.
Fans spin briefly then power cuts out without POST beeps.
An unseated 8-pin EPS12V connector fails to supply stable dedicated voltage to the processor voltage regulator modules (VRMs), resulting in a power fault detection at startup.

Key Concept

CPU Thermal Throttling/Shutdown Mechanisms and EPS12V Auxiliary CPU Power Delivery
Estimated Time:2m 0s
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Topics

Motherboard, RAM, CPU, and Power Issues

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