220-1101 Question 229
Single answer3.3 Compare and contrast RAM characteristics.A technician is upgrading RAM in a small-form-factor office PC that currently has one 8 GB DDR4-2666 UDIMM installed. The motherboard manual states it supports dual-channel memory, DDR4 2400/2666, non-ECC unbuffered modules only, with a maximum of 32 GB total. The user wants the best performance improvement possible while keeping the existing 8 GB module. Which upgrade should the technician recommend?
- A
Install one additional 8 GB DDR4-2666 non-ECC UDIMM in the matching memory channel
- B
Replace the current module with one 16 GB DDR5-4800 DIMM for higher bandwidth
- C
Install one additional 8 GB ECC registered DIMM because ECC improves stability
- D
Install one additional 16 GB DDR4-3200 non-ECC UDIMM to maximize total memory
Show answer and explanation
Correct answer: A
Explanation
This question tests practical RAM selection using key A+ Core 1 memory characteristics: RAM generation, speed, ECC vs non-ECC, registered/buffered vs unbuffered, form factor, capacity limits, and channel configuration. In this scenario, the motherboard documentation is the primary source for compatibility: it supports DDR4 only, specifically 2400/2666 MT/s, non-ECC, unbuffered modules, and dual-channel operation. The best performance upgrade while keeping the existing 8 GB module is to add a matching 8 GB DDR4-2666 non-ECC UDIMM in the paired slot so the system can run in dual-channel mode. This aligns with standard PC manufacturer and motherboard vendor guidance: use supported memory type and matched modules for best compatibility and channel performance. A faster-rated module such as DDR4-3200 does not make the system run faster than the board's supported speed, and mismatched capacities can reduce optimal dual-channel benefits. DDR5 and ECC registered memory are incompatible because they do not match the platform's supported RAM characteristics.
- A. Correct.
Correct. Adding a second 8 GB DDR4-2666 non-ECC UDIMM that matches the existing module is the best choice for both compatibility and performance. It meets the motherboard requirement for DDR4, non-ECC, unbuffered memory and allows the system to operate in dual-channel mode, which improves memory bandwidth compared with a single module.
- B. Incorrect.
Incorrect. DDR5 is not backward-compatible with DDR4 motherboards because the modules use a different slot design and signaling standard. Even though DDR5 offers higher bandwidth, it cannot be installed in a system designed only for DDR4.
- C. Incorrect.
Incorrect. ECC registered DIMMs are typically used in servers and workstations that explicitly support ECC and registered/buffered memory. The motherboard manual specifically requires non-ECC unbuffered modules only, so this memory type would be incompatible despite the common misconception that ECC is a universal stability upgrade.
- D. Incorrect.
Incorrect. Although DDR4 memory is the correct generation and non-ECC UDIMM is the correct general type, mixing an 8 GB module with a 16 GB module may prevent optimal full dual-channel operation across all memory capacity. In addition, the motherboard supports up to DDR4-2666, so a DDR4-3200 module would downclock to a supported speed rather than provide its rated speed. This option increases capacity, but it is not the best choice for the best performance improvement while keeping the existing module.