CAS (Column Address Strobe) Latency (CL) is a latency timing that measures the amount of time that it takes to activate the data column of the module, measured in the number of clock cycles. It is included in many memory part numbers and part descriptions as it is a way to compare the speed of memory modules that run at the same frequency. For example, a 667Mhz memory module that runs with a CL of 4 can access data slightly quicker than a 667Mhz module that runs with a CL of 5. This difference may not be noticeable in everyday use. It may only be noticed when large amounts of data are accessed from RAM, such as high end graphics or video editing.

Some computers will require a certain CAS latency. It may only be able to take 667Mhz memory using CL5 and cannot take CL4 667Mhz memory. Also CL, as well as other latency timings, is relative to the frequency of the memory. CL5 for 800Mhz memory is not the same as CL5 for 667Mhz memory. Al clock cycle at 800Mhz is faster than a clock cycle at 667Mhz memory.

Memory modules can be made in different ways to allow for additional functions. These functions require additional components.

Registered memory has registers or buffers included on the module for a better flow of data which increases data reliability. It also allows for greater memory scalability (larger amounts of RAM can be installed). Because of this, registered memory is used mostly in servers. Some Registered DIMMs come with a parity function. This is used for additional error checking. Your computer's motherboard would have to support parity in order for this function to be used. Parity registered memory can also be used in systems that just take registered memory. In this case, the parity function will not be used. Registered memory includes ECC functionality but not all ECC is registered.

Fully buffered memory takes some of the functions of the memory controller (a chip that controls the data flow of RAM) and puts it on the memory module. This further increases memory scalability. Fully buffered memory cannot be used in a computer that takes registered memory and vice versa. Fully buffered memory includes ECC functionality but not all ECC is fully buffered.

Unbuffered memory is memory that does not include any buffers or registers. It is the most commonly used memory in desktop and notebook computers. You cannot use registered memory or fully buffered memory in a computer that takes unbuffered memory.

ECC (Error Correcting Code) memory includes an additional memory chip which allows the motherboard to detect and correct one bit errors. This increases data reliability and can help identify a failing memory module. All registered and fully buffered memory modules also include ECC functionality. ECC unbuffered memory also exists and is usually used in higher end workstation computers. In some cases, you can use ECC unbuffered memory in a computer that takes unbuffered memory but does not have ECC functionality. It simply will not use this feature of the memory.

Additional memory will not necessarily increase the performance of your computer. It will allow you to run more programs or processes at once or more memory intensive programs. There may be a performance increase if the original amount of memory installed was close to insufficient for the programs and processes you use the computer for.

Yes. In most cases if the computer supports a slower speed, it will clock down to a slower speed as long as it is the correct memory type (DDR, DDR2, etc). However, be aware that the clocking down function depends on the computer and it isn't guaranteed to work in every case.

FAQ: KTM-021011-GEN-16

A memory rank is defined as an area or block of 64-bits (72-bits for ECC) created by using some or all of the DRAM chips on a DIMM. A single-rank ECC DIMM (x4 or x8) uses all of its DRAM chips to create a single block of 72 bits, and all the chips are activated by one chip-select signal from the memory controller chipset. A dual-rank ECC DIMM produces two 72-bit blocks from two sets of DRAM chips on the DIMM, requiring two chip-select signals. The chip-select signals are staggered so that both sets of DRAM chips do not contend for the memory bus at the same time.

FAQ: KTM-021011-KVR-02

You may be experiencing a rank limitation caused by your motherboard. To resolve, you can switch to single rank memory modules or slow the memory bus down to PC2700 (333MHz) specification.

FAQ: KTM-021011-KVR-03

Kingston ValueRam (KVR) is Kingston's standard memory line designed with whitebox users in mind. Kingston ValueRam is engineered to meet industry standard specifications and is rigorously tested to ensure quality. However, it is not tested for compatibility in brand name machines such as Dell, HP, Gateway, Sony, etc., which may require specific memory timings and have limits to the DRAM densities used to support these systems. Nevertheless, if the memory meets the system specifications, you may install it to determine compatibility with your system. For help selecting memory, contact Kingston Sales on +1 800-835-6575 or use our Memory Search at http://www.kingston.com/en/memory/search/Options.

FAQ: KTM-021011-KVR-04

Kingston Branded Memory (system-specific memory) is designed, manufactured and tested to the specification of each brand-name computer system we support. The design is fine-tuned to match the timing of the system, to reduce noise and heat, and allow for the most efficient communication between the memory and the CPU.

Kingston ValueRam Memory (KVR) is designed for generic systems. ValueRam memory is engineered to meet industry-standard specifications and is rigorously tested to ensure quality. Kingston ValueRam is ideal for users who purchase memory by spec and are looking for competitively priced generic memory that is 100 per cent tested to meet industry specifications.

FAQ: KTM-021011-KVR-01

Memory made for a specific brand of computer is only tested with that brand. We can only guarantee compatibility with that brand and no other brand of computer. Nevertheless, if the memory meets the system specifications, you may install it to determine compatibility with your system. For help selecting memory, contact Kingston Sales on +1 800-835-6575 or use our Memory Search at http://www.kingston.com/en/memory/search/Options.

FAQ: KTM-051211-KVR-05

In many cases, the BIOS or a diagnostic program will report the memory bus frequency, which is half of the frequency for DDR type memory. So, if you see that the memory bus speed is 400Mhz and you are using 800Mhz DDR2 memory, the RAM is running at the correct speed.

FAQ: KTM-051911-GEN-20

Typically, the memory sockets (slots) are marked 0, 1, 2, 3 etc… with socket zero being the lowest. If there are no labels on the motherboard, the socket closest to the CPU should be considered socket zero (or the first socket).

In Windows, click on the start button and open "Control Panel". Use classic view for Vista and 7. Then open "System". This will display basic information about the computer including the amount of RAM installed.

In MacOS, select "About This Mac" or "About This Computer" from the Apple menu in the upper left corner of your Desktop. This will provide information about your Mac's total memory (built-in memory plus DIMMs or SIMMs installed).

In Linux, open a terminal window and enter the following command: cat /proc/meminfo

This will show the total amount of RAM as well as other memory information.

FAQ: KTM-012711-GEN-06

Adding memory will not improve internet browsing. It may increase overall system performance and this may cause internet browsing to be improved. But it will not improve internet browsing specifically.

FAQ: KTM-012711-GEN-09

It is not uncommon to hear this happening. A system running the 32bit version of Microsoft Windows 2000, XP, Vista or 7 Operating Systems with 4GB's of physical memory installed will show approximately 3.5GB or less. The reason for it is because Windows will allocate some of the memory to other resources such as to

• System BIOS (including motherboard, add-on cards, etc.
• Motherboards resources
• Memory mapped I/O
• configuration for AGP/PCI-Ex/PCI
• Other memory allocations for PCI devices

Different onboard devices and different add-on cards (devices) will result of different total memory size, i.e. more PCI cards installed will require more memory resources, resulting of less memory free for other uses. If the BIOS is reporting the full 4GB but Windows is not, then it's allocating memory to your PCI resources.

Try enabling the PAE switch in the OS. This has been known to fix the addressing issue. For specific details, please visit Microsoft’s website by clicking on the following link. If you cannot click on it, copy and paste to your web browser.

http://msdn.microsoft.com/en-us/library/aa366796.aspx

If you have, Vista for more info please visit Microsoft’s website. http://support.microsoft.com/kb/929605

FAQ: KTM-012711-GEN-11

First, make sure you have the correct memory for your notebook. Refer to Kingston's online Memory Search at www.kingston.com for assistance. After confirming that you have the correct memory for your system, do the following:

1. Prior to memory installation, first shut down the notebook, then remove the battery pack and unplug the power cord. Reseat the memory firmly into the socket and then push down on the memory to lock it in place. Replace the battery pack and power cord and boot the system. If the installation is still unsuccessful, try inserting the memory into a different slot, if available.
2. If you have properly installed the recommended memory and the PC still does not boot or recognise the memory, you may need to download the latest BIOS from your computer manufacturer's Website.

Note: Kingston is in no way responsible for any problems resulting from flashing the BIOS. Flashing the BIOS is merely a troubleshooting suggestion. Customers who flash the BIOS do so at their own risk. All instructions on how to upgrade the BIOS will be provided by the computer manufacturer or the 3rd party BIOS manufacturer and not by Kingston.

FAQ: KTM-012711-GEN-12

1. Shut down and unplug your computer.
2. Reinsert the memory module(s) with the largest capacity in the first socket followed by the smaller capacities in descending order. To ensure the memory modules are installed properly, line up the memory notches with the key in the memory socket, then push the memory firmly into the socket until the tabs lock the memory into place.
3. Make sure all the cables in your computer are connected properly. You may have failed to connect a needed power connector to the motherboard or accidentally disconnected a cable to your hard drive.
4. If you have properly installed the recommended memory and the PC still does not boot or recognise the memory, you may need to download the latest BIOS from your computer manufacturer's Website.

The full capacity of the module is not properly read. The BIOS may not address the module's chip density properly. Updating the system's BIOS may resolve this problem. Otherwise, you will need to use lower density memory, if available.

Also, if you have a memory kit installed, you may be mistaken on the capacity of the modules you have installed. The capacity shown in a kit part number is the capacity of the entire kit, not each module. For example, the part number KVR800D2N6K2/2G consists of two 1GB modules.

FAQ: KTM-021011-GEN-14

No. Registered and Unbuffered RAM can't coexist. Registered and Unbuffered are two different memory technologies. Installing the incorrect memory or mixing these technologies could cause damage to the motherboard and/or memory module(s).

FAQ: KTM-021011-GEN-15

For desktop computers, shut down and unplug your computer and open the case. Please note: The higher capacity memory should be installed in slot 1 followed by the next lower capacity memory in slot 2 and so on. Please refer to your motherboard manual for proper slot identification.

Remove the memory module as shown in Fig 1. Push the tabs (1) outward and the module will gently pop out of its slot (2). Remove it completely from the slot.

To install the new memory module, see Fig 2. Push the tabs (1) that are at the ends of the memory socket outward and align the memory notches with the key of the memory socket (2), then push the memory down FIRMLY into the socket so the latches lock the memory in place (3). If the memory has been properly installed and you have the correct memory but it is still not being detected, you should make sure you have the most up-to-date BIOS from your computer manufacturer's website.

For notebook computers, please note that you need to shut down the unit and remove the battery pack and power cord before you remove/install memory. Push the memory into the socket FIRMLY so that it makes good contact (it is important to push the memory in FIRMLY) before pushing it down to lock it in place (see figures below) . Once the memory has been installed, put the battery back in your unit and supply power using the power cord and not solely from the battery. If the memory has been properly installed and you have the correct memory but it is still not being detected, you should make sure you have the most up-to-date BIOS from your computer manufacturer's website.

BIOS - Basic Input/Output System is installed on the computer's motherboard. It controls the most basic operations and is responsible for starting your computer up and initialising the hardware. It is data that is usually held on a ROM chip and can be updated by "flashing" the BIOS. BIOS upgrades may correct errors, support new CPUs, and support new hardware including memory. BIOS updates are usually obtained from the computer's manufacturer's website.

*NOTE: Kingston is in no way responsible for any problems resulting from flashing the BIOS. Flashing of the BIOS is merely a troubleshooting suggestion. Customers who flash the BIOS do so at their own risk. All instructions on how to upgrade the BIOS will be provided by the computer manufacturer or the 3rd party BIOS manufacturer and not by Kingston.

FAQ: KTM-012711-GEN-18

Parts sold in kits (denoted by "K2" or "K3"in the part number, e.g. – KVR400X64C3AK2/2G) are specifically packaged for use in Dual or Triple Channel motherboards. Although Dual and Triple Channel technology resides on the motherboard itself (inside the chipset), the memory modules need to be installed in pairs or sets of three for Dual or Triple Channel mode to function properly. Identical modules packaged in a kit work best because the motherboard will be accessing all the memory modules as a single memory location with a wider bandwidth. Kingston suggests the use of modules sold in kits for Dual or Triple Channel enabled motherboards.

FAQ: KTM-020911-GEN-19