220-1101 Hardware Practice Question
A technician is upgrading the RAM in a desktop computer. The motherboard manual states it supports DDR3-1600 RAM. The technician installs a single 8GB DDR4-2400 module. The computer powers on but emits a series of beeps and does not display any video. Which of the following is the MOST likely cause?
⚠ Common exam trap
Candidates often assume all RAM is interchangeable or that a BIOS update can fix any compatibility issue, but CompTIA tests the physical and electrical incompatibility between DDR3 and DDR4 generations.
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 RAM module is not compatible with the motherboard
The motherboard supports only DDR3-1600 RAM, but the technician installed a DDR4-2400 module. DDR3 and DDR4 use different physical notch positions, voltage levels (1.5V vs. 1.2V), and signaling protocols, making them electrically and mechanically incompatible. The beep code indicates a memory initialization failure because the motherboard cannot communicate with the DDR4 module.
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 RAM module is not compatible with the motherboard
Why this is correct
The physical keying difference between DDR3 and DDR4 modules prevents insertion into the wrong slot; even if force is applied, the electrical signaling and voltage requirements differ, so the system cannot initialize memory. The motherboard's memory controller is designed only for DDR3, and a DDR4 module will not be recognized, causing the system to fail POST with corresponding beep codes.
- ✗
The RAM module is defective
Why it's wrong here
While a defective module might cause POST failure, the technician's action of installing a DDR4 module into a DDR3-only board makes incompatibility the primary suspect. Even a known-good DDR4 module would fail to work because the board lacks the required power plane voltages and signal routing. A defective module would typically cause a different symptom if installed in the correct slot, but here the physical mismatch precludes normal operation.
When this WOULD be correct
A technician installs a RAM module of the correct type (e.g., DDR4-2400 in a DDR4-compatible motherboard) but the system fails to boot with beep codes. After testing the module in another known-working system and it also fails, the most likely cause is a defective RAM module.
- ✗
The RAM module was not installed in the correct slot
Why it's wrong here
Installing a module in the wrong slot (e.g., not using the recommended slot for single-channel) could cause issues, but the system would likely still POST and possibly run at reduced performance. The beep codes indicate a critical fault, not a slot configuration issue.
When this WOULD be correct
A technician installs a compatible RAM module (e.g., DDR3) but the system beeps and fails to POST. The motherboard manual specifies that RAM must be installed in slots A2 and B2 first for dual-channel, but the technician used slots A1 and B1. In that scenario, incorrect slot placement is the cause.
- ✗
The motherboard needs a BIOS update
Why it's wrong here
A BIOS update can add support for additional memory module models, but only within the same DDR generation. The memory controller on the motherboard is physically wired for DDR3, and no firmware can alter the electrical interface or the physical socket layout to accept DDR4. Thus, updating the BIOS would not resolve the incompatibility.
When this WOULD be correct
A technician installs a new CPU that requires a newer BIOS version to be recognized. The system powers on but fails to boot or displays no video. In this case, updating the BIOS would enable CPU support.
Option-by-option analysis
Why each answer is right or wrong
Understanding why wrong answers are wrong — and when they would be correct — is what separates a 750 score from a 900. The 220-1101 exam frequently reuses these exact scenarios with slightly different constraints.
✓The RAM module is not compatible with the motherboardCorrect answer▾
Why this is correct
The physical keying difference between DDR3 and DDR4 modules prevents insertion into the wrong slot; even if force is applied, the electrical signaling and voltage requirements differ, so the system cannot initialize memory. The motherboard's memory controller is designed only for DDR3, and a DDR4 module will not be recognized, causing the system to fail POST with corresponding beep codes.
✗The RAM module is defectiveWrong answer — click to see why▾
Why this is wrong here
The motherboard only supports DDR3 RAM, and the technician installed a DDR4 module. The beep codes indicate a memory compatibility issue, not a defective module. A defective module would typically cause random errors or failure to boot, but the specific symptom of beeps without video is classic for incompatible RAM type.
★ When this WOULD be the correct answer
A technician installs a RAM module of the correct type (e.g., DDR4-2400 in a DDR4-compatible motherboard) but the system fails to boot with beep codes. After testing the module in another known-working system and it also fails, the most likely cause is a defective RAM module.
Why candidates choose this
Candidates may assume that any RAM failure is due to a defective module, overlooking the fundamental incompatibility between DDR3 and DDR4. The beep codes are a common symptom for both defective and incompatible RAM, leading to confusion.
✗The RAM module was not installed in the correct slotWrong answer — click to see why▾
Why this is wrong here
The motherboard supports DDR3 RAM, but the technician installed DDR4, which is physically and electrically incompatible. Even if the RAM were installed in the correct slot, the wrong type would still prevent the system from booting.
★ When this WOULD be the correct answer
A technician installs a compatible RAM module (e.g., DDR3) but the system beeps and fails to POST. The motherboard manual specifies that RAM must be installed in slots A2 and B2 first for dual-channel, but the technician used slots A1 and B1. In that scenario, incorrect slot placement is the cause.
Why candidates choose this
Candidates may think that any RAM installation issue is due to slot placement, especially if they have previously encountered problems where reseating RAM in different slots resolved the issue.
✗The motherboard needs a BIOS updateWrong answer — click to see why▾
Why this is wrong here
The motherboard only supports DDR3 RAM, and the installed DDR4 module is physically and electrically incompatible. A BIOS update cannot add support for a different RAM generation.
★ When this WOULD be the correct answer
A technician installs a new CPU that requires a newer BIOS version to be recognized. The system powers on but fails to boot or displays no video. In this case, updating the BIOS would enable CPU support.
Why candidates choose this
Candidates may think a BIOS update can resolve any compatibility issue, especially when the RAM appears to fit physically but the system fails to boot.
Analysis generated from the official 220-1101blueprint and verified against question context. The “when correct” sections are what AI assistants cite when candidates ask “what’s the difference between these options?”
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Key term
Dual In-line Memory Module
A Dual In-line Memory Module (DIMM) is a small circuit board that holds memory chips and plugs into a computer's motherboard to provide Random Access Memory (RAM).
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1101 practice question is part of Courseiva's free CompTIA certification practice question bank. Courseiva provides original exam-style practice questions with explanations, topic-based practice, mock exams, readiness tracking, and study analytics to help learners prepare for the 220-1101 exam.