3.9.6 Practice Questions Troubleshooting Memory, 3.8.8 Practice Questions Memory Installation

After installing two memory modules, you power on the system to check for errors. You find that the BIOS program recognizes only one of the memory modules. What should you do first?

Make sure that both modules are seated properly in their slots. Explanation In this case, you should check to ensure that you installed the memory correctly. Most BIOS programs include a memory count that displays the total amount of system memory. If it does not count the proper amount of memory, begin by checking to make sure the memory is inserted correctly. After the memory is installed correctly, if it is still not recognized, try removing one module to identify which module has the problem. Move the modules to different motherboard slots to see if you can get the system to detect the memory. In most cases, you will not need to change the memory timings. When you do, it is typically because the system is unstable or crashes. Testing memory helps you identify when specific memory storage locations are going bad. Device Manager will not enable memory not recognized by the BIOS.

You are in the process of configuring a new computer. The motherboard has four memory slots and supports dual-channel memory. You install two memory modules. When you boot the computer, the BIOS recognizes both modules, but the memory is not configured to run in dual-channel mode. What should you do?

Move the modules to the correct motherboard slots. Explanation To use dual-channel memory, you will need to install memory in the correct slots. Depending on the motherboard, the two slots might be next to each other, or alternating. Consult the motherboard documentation for the correct configuration. Dual- channel support is mainly a function of the motherboard (e.g., the memory controller), not the memory itself. Continuity modules are used with Rambus RAM; if continuity modules were required on this system, non of the memory would have been detected. The CAS latency is used for memory timing. You might modify the timing if the system is unstable at the current memory timing settings.

You are in the process of configuring a new computer. The motherboard has six memory slots and supports triple-channel memory. You install two memory modules. When you boot the computer, the BIOS recognizes both modules, but the memory only runs in dual-channel mode. What should you do?

Install a third, identical memory module. Move the modules to the correct motherboard slots. Explanation To use triple-channel memory, you will need to install 3 or 6 memory modules in the correct slots. Depending on the motherboard, the slots might be next to each other, or alternating. Consult the motherboard documentation for the correct configurarion. Triple-channel support is mainly a function of the motherboard (i.e. the memory controller), not the memory itself. Continuity modules are used with Rambus RAM; if continuity modules were required on this system, none of the memory would have been detected, The CAS latency is used for memory timing. You might modify the timing if the system is unstable at the current memory timing settings.

You have installed a new computer with a quad-core 64-processor 6 GB of memory, and a PCIe video card with 512 MB of memory. After installing the operating system, you see less than 4 GB of memory showing as available in Windows. What should you do?

Install a 64-bit version of the operating system. Explanation In this scenario, the most likely cause is the operating system being a 32-bit operating system. You must use a 64-bit operating system to use memory above 4 GB. The AGP aperture is a method for sharing system memory with an AGP (not PCIe) video card. With shared memory, some of the memory is used by the video card and is not available for the system.You do not update memory controller drivers.

Which of the following is an error detection technique that can detect errors with only one bit?

Parity Explanation Parity error detection can only detect errors with only one bit. EDO is not a type of error correction, it is a type of memory that can start a new access cycle while keeping the data output of the previous cycle active.

Which of the following is an error detection technique that can also correct the error?

ECC Explanation Error Correcting Code (ECC) can detect and correct errors. Parity error detection techniques can detect errors but cannot correct them. The data must be resent. EDO is not a type of error detection., it is a type of memory that can start a new access cycle while keeping the data output of the previous cycle active.

You have just a built a new system from scratch. You turn the computer on but the system boot fails and sounds a beep code.

What might be the issue?

Memory not installed or not detected. Explanation If memory was not installed in the new computer or was not detected during boot up, system boot will fail and sound a beep code. If unsupported memory was installed, the system will boot but the display will be blank. If incompatible memory was installed, such as combining dual-bank with single-bank memory, the system will boot but the memory count will be incorrect. If a mix of new and old memory was used, the system will boot but will display a memory error message.

Which type of software-generated problems can indicate that a software bug is causing a memory error?

General- protection fault. Exception error. Page fault. Explanation Software-generated memory problems include the following: Exception error General-protection fault. Page fault. Registry errors indicate that parts of the registry are written to faulty sections of RAM. Parity interrupt usually indication a falling module or discrepancies between new and old memory. An incorrect memory count can happen with incompatible memory installation; remember to avoid combining dual-bank with single-bank memory.

You just replaced the motherboard in your computer. Now your computer will not start. You press the power button on the system case, but nothing happens; there are no sounds or lights.

What should you do?

Connect the power button to the motherboard. Explanation The system case power button connects to jumper pins on the motherboard, When you press the power button, the cable sends the power on signal to the computer. If the power button was connected, you would typically hear fans start up and see lights come on as the system boots. Even without a processor fan, memory, or a keyboard or mouse you still see or hear something if the system had power.

This can require more memory and can cause problems if there is not enough memory at this time.

Software installation

Memory is not properly seated, missing, or the motherboard is defective.

First boot of a new computer.

Incompletely or improperly doing this can cause errors that appear to be memory related.

Hardware installation or removal.

The memory is not compatible and was not installed and configured properly.

Memory upgrade

Explanation

At these critical times memory problems can manifest themselves: First boot of a new computer- memory is not properly seated, missing, or the motherboard is defective. After a memory upgrade-ensure that the memory is compatible and was installed and configured properly. After software installation-new software can require more memory and can cause problems if there is not enough memory for the software. After hardware installation or removal-incompletely or improperly installed hardware can cause errors that appear to be memory related.

You are attempting to boot a new system. The boot fails and the system sounds a beep code.

Which of the following describes the most likely cause of this error?

Either no memory is installed or the memory was not detected. If the system boot fails and sounds a beep code, the most likely cause is that either no memory is installed or the memory was not detected. If a card or memory module is not seated, or the system includes unsupported memory, the system will boots, but the display will remain blank. If POST fails to recognize all of the memory, the system will boot, but the memory count will be incorrect.

Which of the following statements is true regarding single-and double-sided memory?

Single-sided memory uses half the number of memory modules as double-sided memory of the same capacity. Explanation Single-sided memory uses half the number of memory modules as double-sided memory of the same capacity. Single-sided RAM has memory modules that are organized into a single logical bank; double-sided RAM has modules organized into two banks. Because the computer can only access data in one bank at a time, single-sided RAM allows access to all of the memory, while with double-sided RAM, the computer must switch between banks. Originally, double-sided RAM had modules on both sides of the circuit board, and single-sided RAM had modules on only one side. However, you can also have double-sided RAM with modules on only one side, where internally the memory is divided into separate banks.

Which of the following are true regarding a dual-channel memory bandwidth configuration?

The memory controller must support dual-channels. Bandwidth is increased by 5-15% Explanation Dual-channel systems increase the memory bandwidth by only 5-15%, although it does have a 100% theoretical increase. Dual-channel support is mainly a function of the motherboard (e.g., the memory controller), not the memory itself. DDR, DDR2, and DDR3 can all work in dual-channel systems (depending on the memory supported by the motherboard); a triple channel system can only use DDR3.

You have a computer with a Pentium 4 CPU and two PC-2400 DDR modules. The motherboard has room for two additional memory modules, and you’d like to install two PC-4000 modules. Which of the following statements is true?

All memory will operate at 300 MHz. Explanation In this scenario, all memory will operate at 300 MHz. When you mix memory with different speed ratings, all memory will operate at the slowest frequency. Memory can operate at a frequency lower than its rating. The only way to get memory to operate at a higher frequency is to overclock the memory. However, memory is tested and rated at the highest frequency at which it is stable. While you can likely get some small performance gains through overclocking, it is unlikely that you will be able to push the PC-2400 memory up to PC-4000 and still have a stable system.

You have a computer that has four DDR2 memory slots. Currently there are two 512 MB memory modules installed. You check the motherboard documentation and find that the system has a 4 GB memory limitation. You want to add as much memory as possible without replacing the existing modules.

What is the maximum total amount of RAM that can be installed in this system?

3 GB Explanation You can add more memory to the system bringing the total to 3 GB. The system currently has 1 GB of RAM. Because the motherboard has a 4 GB memory limit, there is also a 1 GB limit for each memory slot. Adding two 1 GB modules brings the total to 3 GB.

You have an existing system that has a single DDR3 memory module installed. You would like to add more memory to the three remaining empty memory slots. What should you do to make sure you get the right memory for the system?

Check the motherboard documentation to find which modules are supported. Purchase additional modules that are the same as what is currently installed. Explanation To purchase the correct memory for your system, you can: – Check the motherboard documentation or the motherboard manufacturer’s website to identify supported memory modules. – Purchase modules that are the same as what is currently installed. Be aware, however, that some motherboards may have limitations on the capacity of modules supported. For example, if a motherboard has four slots, you might be able to fill all slots only when memory modules are 1 GB or smaller. If you use larger modules, you may not be allowed to fill all of the slots. – Use an online configuration tool from a leading memory manufacturer to identify supported modules. Updating the BIOS might enable the motherboard to support newer memory modules, but you will still need to verify which modules are supported.

You want to upgrade all memory in your system with the fastest memory available. Which of the following should you choose?

Choose the type of memory that is supported by your motherboard. Explanation Different memory module form are not interchangeable. A motherboard will only accommodate one type of memory. Subsequently, the fastest memory in this will be the memory that fits in the system.

You want to build a new system that supports 6 GB of memory. Which of the following will be the most important when building the computer?

64-bit processor Explanation To use over 4 GB of memory, you will need a 64-bit processor and a 64-bit operating system. 32-bit processors support up to (or slightly below) 4 GB of memory. While 6 GB of memory will likely use DDR2, DDR3, or DDR4, this is not a requirement. Triple channel memory uses three memory controllers to improve memory performance. ECC memory includes error correction on the memory.

Which of the following is the most common method for removing RAM from a motherboard?

Move the tabs holding the RAM out of the way; pull straight up to remove the RAM. Explanation Most RAM is held in place with small tabs on either end. Push the tabs down to rotate them back, then pull the RAM straight up.

What type of RAM might slow system performance because it holds memory addresses or data to improve stability on systems with more than 1 GB of RAM before it is transferred to the memory controller?

Buffered Explanation Buffered (or registered) RAM has a buffer that holds memory addresses or data before it is transferred to the memory controller. Buffered RAM improves stability on systems with a lot of RAM (over 1 GB) but it might slow system performance. Unbuffered memory does not have a buffer to hold memory addresses or data before it is transferred to the memory controller. Unbuffered memory can be found in servers and high-end workstation. Parity memory is a type of memory that checks for common kinds of internal data corruption. It does not correct internal data corruption. Non-parity memory does not perform error checking. EEPROM is RAM chip that holds non-volatile memory used in computers and other electronic devices to store relatively small amounts of data.

With a memory module read request, there is a delay between the time of the data request and the time the data is available for output from the memory module.

What is this delay called?

CAS Latency Explanation A factor that affects the performance of memory is the latency associated with accessing data in RAM. With a memory module read request, there is a delay between the time the data is requested and the time that the data is available on the module’s output pins. This delay is called the CAS latency (CL). CL is expressed in the number of clock cycles that pass between the time of the request and the moment the data is available. Given memory modules of the same type and frequency, a lower CL indicates which memory module is faster. Frequency, also referred to as speed, is a major factor in measuring how fast or slow a memory module is. Capacity, also referred to as size, indicates how much data a memory module can store Clock cycle parity is a fictional concept.

You are in a carpeted office lighted by fluorescent bulbs. You are preparing to add memory modules to a user’s computer. The user has already unpacked the memory modules and stacked them on top of an old, unused CRT monitor.

What is the greatest threat in this environment that could damage these memory modules?

Electrostatic discharge (ESD) Explanation Memory modules are very sensitive to ESD. It’s possible that the memory modules have already been damaged by the possible lack of proper ESD prevention if the user removed the modules from the packaging while standing on the carpeted floor. But you can still take proper steps to prevent ESD before you proceed to install the modules. The CRT monitor is not likely to emit a high voltage discharge unless you take it apart. An unused CRT monitor does not emit a strong magnetic field and memory modules are not susceptible to magnetic fields. Memory modules are also not susceptible to electromagnetic interference.