easyMultiple ChoiceObjective-mapped
220-1201 Motherboard memory limit Practice Question
A customer reports that their desktop PC, which originally had 8 GB of RAM, is now very slow after they installed a second 8 GB stick. The system boots and shows 16 GB in the BIOS, but the OS only reports 8 GB usable. What is the most likely cause?
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 motherboard only supports up to 8 GB of RAM.
The most likely cause is that the motherboard has a 8 GB maximum memory limit, often due to chipset or BIOS limitations. Even if the BIOS detects 16 GB installed, the OS cannot address beyond the supported limit, resulting in only 8 GB usable. This is a common occurrence on older motherboards or those with a 32-bit UEFI.
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 stick is faulty and needs to be replaced.
Why it's wrong here
Faulty RAM typically causes boot failures, crashes, or memory errors, but does not result in the OS showing exactly half the installed memory while BIOS sees full capacity.
- ✗
The RAM is not fully seated in the slot.
Why it's wrong here
If the RAM were not fully seated, the system would likely fail to boot or the BIOS would not detect 16 GB.
- ✗
The new RAM stick is incompatible with the existing module, causing the system to run in single-channel mode and limiting usable memory.
Why it's wrong here
Incompatible RAM (mismatched speed/timings) may cause performance degradation or instability, but does not reduce total usable memory; the OS would still report 16 GB.
- ✓
The motherboard only supports up to 8 GB of RAM.
Why this is correct
If the motherboard's chipset or BIOS has a maximum memory limit of 8 GB, the OS will only report 8 GB usable even if BIOS detects 16 GB installed.
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Written by Johnson Ajibi, MSc IT Security
Senior Network & Security Engineer · founder of Courseiva
This 220-1201 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 220-1201 exam.