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IT Support & Hardware · Intermediate

Debug LED

Motherboard indicator lights or a two-digit display that show which POST stage failed.

Definition

Modern boards have Q-LEDs (CPU, DRAM, VGA, BOOT) or hexadecimal POST code displays. The last lit LED points to the subsystem that failed initialization. They replace beep codes on many boards without speakers.

Example

A steady DRAM LED means reseat or test the memory modules.

Exam tip

Use debug LEDs to narrow a no-POST issue before swapping parts.

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