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220-1101 Hardware Practice Question

A technician is upgrading a desktop PC by adding two additional 8GB DDR4-3200 RAM sticks to an existing pair of 8GB DDR4-3200 sticks. After installation, the system powers on but does not POST; the fans spin and the power LED is on, but no display appears. The technician has reseated all four sticks and verified they are fully clicked into place. The original two sticks alone allow the system to boot normally. Which of the following is the MOST likely cause of the issue?

⚠ Common exam trap

It's easy for candidates to assume any POST failure with new RAM must be due to incompatibility (Option A) or defective hardware (Option D), but the CompTIA 220-1101 exam tests understanding of memory rank and controller load limitations, which is a subtle but critical concept.

Answer choices

Why each option matters

Answer the question above first, then reveal the full breakdown to understand why each option is right or wrong.

Correct answer & explanation

✓

The memory controller cannot handle the combined load of four dual-rank modules, causing memory training failure during POST.

The most likely cause is that the memory controller cannot handle the combined load of four dual-rank modules, leading to memory training failure during POST. With four dual-rank sticks, the electrical load on the memory bus increases significantly, which can prevent the system from completing the initial memory training sequence. This is a common issue on consumer platforms where the memory controller is optimized for two modules or single-rank configurations, and the original two sticks alone boot normally because they present a lighter load.

Answer analysis

Option-by-option breakdown

For each option: why learners choose it and why it is or isn't the right answer here.

✗
The new RAM sticks are of a different DDR generation (e.g., DDR3) and are not compatible with the motherboard.
Why it's wrong here
The technician verified the new modules are DDR4-3200, exactly matching the generation and speed specification. DDR3 and DDR4 modules are physically keyed differently and use different voltage levels (1.5V/1.35V for DDR3 vs. 1.2V for DDR4), so a DDR3 stick cannot even be inserted into a DDR4 slot. Since the modules are confirmed as DDR4 and the system only fails when all four are populated, a generation mismatch cannot explain the no-POST condition.
✗
The motherboard does not support running four memory modules simultaneously; it only supports two modules in dual-channel mode.
Why it's wrong here
Most consumer motherboards support four memory modules, though some budget boards may have limitations. However, the specification often allows four modules, but the system may fail to POST if the memory controller cannot handle the combined load. The more precise issue is not about the number of modules but about the memory rank and timing compatibility.
✓
The memory controller cannot handle the combined load of four dual-rank modules, causing memory training failure during POST.
Why this is correct
If the existing two sticks are dual-rank (most 8GB sticks are), adding two more dual-rank modules results in four ranks per channel, which many memory controllers (especially on older chipsets like Intel 300-series) cannot support. This causes the system to fail to initialize memory, resulting in no POST. Using single-rank modules or reducing speed often resolves the issue.
✗
The new RAM sticks are defective, as they do not match the speed of the original sticks.
Why it's wrong here
The technician verified they are the same speed (DDR4-3200). While defective sticks are possible, the fact that the system fails only with all four sticks and works with either pair alone suggests a compatibility issue rather than a single defective component. Swapping the sticks would likely show the same symptom.

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220-1101 Hardware Practice Question

Why each option matters

Option-by-option breakdown

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