Frequently Asked Questions - DRAM

The Cisco UCS Manager uses a catalogue system to identify DIMMs. In some situations, for example where the UCS Catalogue in service is not the most recent, or if the Integral components are not recognised, then these messages will be reported for servers with Integral memory installed.

However, there is absolutely no impact on the memory performance and these messages can be safely ignored.

 

The short answer is - No. Using the correct corresponding Integral memory modules will NOT invalidate your warranty.

For more information please click to read our help guide.

CAS Latency (CL) stands for Column Address Strobe. This is the number of clock cycles that pass from when an instruction is given for a particular column and the moment the data is available. In general the lower the CAS latency the better within a given memory technology (DDR, DDR2 or DDR3). Typical values are;

  • DDR -  2.5, 3 Cycles
  • DDR2 - 3, 4, 5, 6 Cycles
  • DDR3 - 7, 9  Cycles

DDR, DIMMS and SODIMM are both memory modules used in computers.

DIMMs are used in desktop computers and servers. A DIMM (133MM) is about twice as long as a SODIMM (67MM). DIMMs can carry features not normally found on SODIMMs such as ECC and REGISTERED.  

SODIMMs are used in notebook computers.

Please see our SODIMM and DIMM guide.

A RANK is a 64bit (or in a case of an ECC module 72bit) data width addressable area of a memory module.

Currently a module can be:
SINGLE RANKED (Rank 1  ) or
DOUBLE RANKED (Rank 2) or
QUAD RANKED (Rank 4 ).

1 RANK = 64bit width (or 72bit with ECC)

Single Rank  = 64bit

Double Rank = 64bit + 64 bit

Quad Rank  =  64bit + 64 bit + 64bit + 64 bit

Ranks are for interleaving to make a system run faster. This is where one device or part of a device is being accessed for data whilst another device or part of a device is getting ready to deliver data.

On some server upgrades there will be a maximum number of ranks a server will address or certain ranked modules may need to be fitted to certain sockets. For example, if a server can address 8 ranks. It may take a variation of 1GB, 2GB, 4GB and 16GB module to achieve this.

For 2GB modules the server may take:
4 x 2GB Rank 2 modules = 8 Ranks with 8GB or

8 X 2GB Rank 1 modules = 8 Ranks with 16GB

or alternatively using 16GB modules,
2 X 16GB Rank 4 modules = 8 Ranks with 32GB

Some planning is required when completing some server upgrades that need ranking, as installing the incorrect amount or type of ranks may lead to problems, or memory may need to be removed and replaced in the future to achieve the maximum density of memory if all sockets are used. Please check your user manual

Below are memory modules currently available from integral memory.

Technology DDR DDR2 DDR3
Density      
256MB RANK 1    
512MB RANK 1 or 2 RANK 1 or 2  
1GB RANK 1 or 2 RANK 1 or 2 RANK 1
2GB RANK 1 RANK 1 or 2 RANK 1 or 2
4GB   RANK 2 or 4 RANK 2 or 4
8GB   RANK 2 RANK 2 or 4
16GB     RANK 4

 

Normally the amount of installed memory will show when you print a status page. Please refer to your device's handbook for instructions on how to do this.

Use our memory Configurator www.integralmemory.com/config or you can consult any user handbooks that may have been supplied with your computer. Or please contact us if your have any problems

DDR3 can be used with the Intel Core i processors. When modules are installed in identical kits of 3, the memory controller can interleave between all 3 thus reducing wait states and increasing performance.

No. DDR, DDR2, DDR3 are different. You must select the correct type to match your system. DDR, DDR2 and DDR3, DIMM and SODIMM modules have notches in different places to prevent insertion into a incompatible system. See our memory guides; DIMM or SODIMM. Below are some basic differences.

 

Speed (MHZ)

Technology

DIMM (Pins)

SODIMM (Pins)

Voltage (V)

DDR

266

PC-2100

184

200

2.5

 

333

PC-2700

184

200

2.5

 

400

PC-3200

184 

200

2.5

 

 

 

 

 

 

DDR2

533

PC2-4200

240

240

1.8

 

667

PC2-5300

240

240

1.8

 

800

PC2-6400

240

240

1.8

 

 

 

 

 

 

DDR3

1066

PC3-8500

240

204

1.5/1.35

 

1333

PC3-10600

240

204

1.5/1.35

Fully Buffered DIMMs are used in servers to increase reliability and to access more memory within a system.

Fully Buffered DIMMs (FB-DIMM) have an AMB (Advanced Memory Buffer) unlike other buffers this has a Serial Interface to the memory controller, this allows greater data width without having to increase the number of pins on the memory controller. This method is only used in DDR2 modules.

FB-DIMMS have 240 pins and are the same length as DDR DIMMS but differ by having notches in different positions so standard DDR2 modules will not fit into a FB-DIMM system.  FB-DIMMs require a FB-DIMM compatible system.

Click here for DIMM Guide with images.

The notches move depending on physical characteristics of the module.
One moves depending on Voltage, the other moves depending if the module is Unbuffered or Buffered. This was introduced so only modules of the correct type can fit in the sockets.

 

A nanosecond (ns) is one billionth of a second (10-9 s).
They are used to show the length of time a memory chip takes to complete a single read/write cycle.

The most common reason is that the machine is designed to work in Dual Channel Mode where the memory controller utilises a pair of modules in turn (interleaving) so that it can reduce the time that it waits whilst the memory is read giving a better performance.

 

POST (Power On Self Test) occurs as the computer is turned on. The BIOS checks each necessary component is responding and reads info for access timings. In the case of memory modules, it will read the SPD (Serial Presence Detect) to check compatibility and access timings. If the wrong type of memory is installed or if the memory has become faulty - there may be a POST error reported, sometimes with beeps.

 

The SPD (Serial Presence Detect) chip on a memory module is an additional chip holding 128Hex bytes of information about the module.

This identifies the module to the BIOS during POST so the Motherboard knows its characteristics and timings that can be used. This was introduced at the same time as SDRAM. 

Single Data Rate (SDR) SDRAM has been superseded by faster Double Data Rate (DDR RAM)
DDR RAM with a Double Data Rate is achieved this by "double pumping" (transferring data on both the rising and falling edges of the clock signal), hence double the data rate. The other differences include : number of pins, voltage, speed and latency.  

SDRAM will not fit or work in a DDR system and vice-versa.

SDRAM (Synchronous Dynamic Random Access Memory) is the term used for all memory that run with timing cycles that are synchronous to the Motherboard. Prior to SDRAM, memory ran in its own clock cycle which caused waiting time for the CPU.

SDRAM was introduced at the same time as the 133Mhz Pentium Processor.

As silicon technology advances we are able to fit more capacity in a single chip. This means we need less chips to make the same capacity module. Therefore an earlier version may have 8 chips and a newer version may have 4 giving the same capacity.

The phrase Dual-Channel memory is incorrect. The true statement is Memory in Dual-Channel mode. This refers to a machine utilising a pair of modules processing the data more efficiently and reducing system latencies (interleaving). If your machine is Dual-Channel mode compatible then you will see the benefit when using compatible memory in pairs.

 

No. Data is not stored in DRAM memory once the computer is turned off. All data is stored on your hard drive (HDD) or Solid State Drive (SSD).

Yes it can.
Depending on the type of applications you are using, Windows OS will often use Virtual memory if there is not enough Physical memory.

Virtual Memory utilises the Hard drive, which uses approximately 30 times more power than Physical memory. So more memory can lead to less hard drive use, therefore saving power.

There are 2 considerations which affect the amount of memory that can be installed in your computer.

1) The type and maximum amount of memory that can be installed depends on your motherboard. Use our Configurator to find out how much can be installed. (Alternatively please refer to your computer's handbook or manufacturer's website)

2) The version of your  operating system will have a maximum that it can utilise, which may differ from you computers motherboard. You may be able to install more memory on motherboard than your operating system can access. ( Please refer to your operating system manual or see the table below for guidance)

 

Desktop Operating System Version   Max Memory
       
Windows 7      
  32bit Starter   2GB
  32bit All Other   4GB
 

64bit Home Basic

   8GB
  64bit Home Premium   16GB
  64bit Professional   192GB
  64bit Enterprise   192GB
  64bit Ultimate   192GB
 Windows Vista      
  32bit Starter   1GB
  32bit All Other   4GB
  64bit Home Basic   8GB
  64bit Home Premium   16GB
  64bit Professional   192GB
  64bit Enterprise   192GB 
  64bit Ultimate   192GB
Windows XP      
  32bit Starter   512MB
  32bit Home   4GB 
  32bit Professional   4GB
  64bit Professional   128GB
Windows 2000      
  Professional   4GB
       
Mac      
  OS X   8GB
  OS 9   1.5GB
       
Red Hat Linux      
  2.4 Kernel   64GB 

 

Server Operating System Version Max Memory
       
Windows  2008      
  32bit Web Server   4GB
  32bit Standard   4GB
  32bit Datacenter   64GB
  32bit Enterprise   64GB
  64bit Web Server   32GB
  64bit Standard   32GB
  64bit Datacenter   2TB
  64bit Enterprise   2TB
       
Windows 2003      
  32bit Web Server   4GB
  32bit Standard   4GB
  32bit Datacenter   128GB
  32bit Enterprise   64GB
  64bit Standard   32GB
  64bit Datacenter   2TB
  64bit Enterprise   2TB
  64bit Small Business   128GB
       
Windows 2000      
  Server   4GB
  64bit Home Premium    

Jedec is the Joint-Electron-Device-Engineering-Council, an important body that sets the standards in the memory industry.

Areas like the dimensions and functionality of DIMMS are set by JEDEC. This ensures compatibility.

 

An SoDIMM (Small Out-Line Dual In-Line Memory Module) is a smaller type of memory module used in notebook computers. An SODIMM is about half the size of a module (DIMM) used in desktop PCS. Please click here to see our guide

 

 

  • A SIMM (Single In-Line Memory Module) has a single line of connectors. Connectors on each side of the Board are the same. SIMMs are now obsolete.
  • A DIMM (Dual In-Line Memory Module) has 2 lines of connectors. Connectors on each side of the board are not connected. The most popular types of DIMM are DDR, DDR2 and DDR3

 

In general yes, count the total number of memory chips on the module. If the number of data chips can be divided by 3 then the module has ECC. (i.e. ECC will have an odd number of data chips)

Parity is a method of checking for data corruption in memory. One check-bit is added to each byte (8 bits). Errors are detected, but not corrected.

ECC stands for ERROR CORRECTING CODE.

This uses technology on the motherboard to test the accuracy of of outgoing and incoming data by using a checksum. Some errors are automatically corrected, ECC modules are normaly used in high end workstations and servers where data integrity is vital. ECC applies to DDR, DDR2 and DDR3 modules.

ECC modules have a extra memory chip for every eight chips. eg  9 or 18 as opposed to 8 or 16 for a NON-ECC module.

In most cases you can install a ECC module into a NON-ECC system but generally a ECC system will require a ECC module. Please check your PC manual.

 

Physical and Virtual memory are two different things. Virtual memory allows you to use some of your hard drive as though it were RAM. Your hard drive is up to 100 times slower than RAM. When you upgrade your RAM, you can reduce or eliminate the use of virtual memory. Upgrading RAM makes more (physical) memory available to complete tasks previously handled by virtual memory.

ESD (Electrostatic Discharge) is static electricity. ESD occurs when touching an object that conducts static electricity. ESD can damage memory modules.

To protect your memory module from ESD, always store components in antistatic packaging until use. Before handling memory modules we recommend you discharge any static by touching an earthed metal object such as a nearby unpainted radiator or pipe.

ESD wrist straps can be purchased to provide additional ESD protection.

In general yes it will speed up your computer.

Additional memory will not increase the speed of the CPU, however it will reduce the time a CPU spends waiting for information from the hard drive. RAM provides data to a CPU faster than a hard drive, so it will not take as long for programs to execute. If your system is running slow and you have less than the ideal amount of memory, -increasing the memory is an easy way of boosting system performance. 

• Windows users - Right mouse-click on the "My Computer" icon and select "Properties." The total memory is calculated and displayed under the "General" tab in the system properties window.


• Mac users - 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).

DDR can manipulate data two times per clock cycle. This means the output is twice that of the front side BUS (FSB).

DDR Output FSB Peak Bandwidth
PC1600 200Mhz 100Mhz 1.6GB/sec
PC2100 266Mhz 133Mhz 2.1GB/sec
PC2700 333Mhz 166Mhz 2.7GB/sec
PC3200 400Mhz 200Mhz 3.2GB/sec

DDR2 Output FSB Peak Bandwidth
PC2-3200 400Mhz 200Mhz 3.2GB/sec
PC2-4200 533Mhz 266Mhz 4.2GB/sec
PC2-5300 667Mhz 333Mhz 5.3GB/sec
PC2-6400 800Mhz 400Mhz 6.4GB/sec

DDR2 3 Output FSB Peak Bandwidth
PC3-6400 800Mhz 400Mhz 6.4GB/sec
PC3-8500 1066Mhz 533Mhz 8.5GB/sec
PC3-5300 1333Mhz 666Mhz

10.6GB/sec

Normally the memory module sockets (slots) are marked 0, 1, 2, 3 etc... with socket zero being the lowest. If there are no markings on the motherboard, the socket nearest to the CPU is normally considered socket zero (or the first socket).

 

CL stands for CAS (Column Access Strobe) Latency, which is a term referring to the time that it takes to retrieve data from the module.

  • CL2 and CL3 refer to the amount of clock cycles that it takes before the initial stream of data is sent.
  • CL2 modules wait two clock cycles before sending data.
  • CL3 modules wait three clock cycles before sending data.
  • CL2 modules are faster since they only wait two clock cycles. Some systems may specify either CL2 or CL3 memory.

UNBUFFERED - No buffer the memory is connected directly to the chipset controller,  DDR, DDR2 and DDR3 modules that are used in desktops or notebooks are mostly unbuffered.

BUFFERED - A buffer is used to help the system control large amount of memory. Used to describe older technology modules such as EDO and SDRAM. Used in servers

REGISTERED - Registered modules do not have a buffer but do contain a register that delays all information transferred to the module by one clock cycle, this increases reliability and applies to DDR, DDR2 and DDR3 modules used in many servers.

FULLY BUFFERED - please see FAQ . Applies only to DDR2 modules used in servers

All SDRAM is backward compatible and can run at any bus speed slower than its rating.
A PC133 SDRAM DIMM is capable of running at 133MHz, 100MHz, and 66MHz.
There are some older motherboards that require 66MHz SDRAM and that will not accept PC100 or PC133 SDRAM, but they are very few.

Please use our Memory Configurator to find compatible modules to upgrade your computer.

www.integralmemory.com/config

Yes. In most cases a PC will accept PC133 modules even though it is designed for PC100. However the modules will only work at the PC100 speed.

Most motherboards that do not have an ECC function within the BIOS are still able to use a module with ECC, but the ECC functionality will not work.

Keep in mind, there are some cases where the motherboard will not accept an ECC module, depending on the BIOS version.

There is nothing wrong with the memory or the computer itself. 32-bit versions of Windows OS have a limit of 4GB RAM, so no more than this is recognised by the OS. The total includes for example, any memory located on attached devices (e.g. sound card, video card).

So if your video card has 512MB of memory and you install 4GB of RAM on the motherboard, the amount shown by Windows OS will be 3.5GB.

You can use memory modules of different speeds as long as they are faster than those specified for your computer. It is recommended to use modules of the same speed as those already installed in your system. If you do mix speeds, the modules will all run at the speed of your slowest modules.

For example, for a DDR2 667MHz system you could add 800MHz modules, they will run at the 667 speed.

You cannot mix DDR, DDR2, DDR3 in a system as each technology requires a different type of socket.

Click here to see our product pages for more information 

Speeds available from INTEGRAL MEMORY


Technology Type Speed  Bus Speed
DDR3 PC3-10666 1333MHz 667MHz
DDR3 PC3-8500 1600MHz 800MHz
       
DDR2 PC2-4200 533MHz 266MHz
DDR2 PC2-5400 667MHz 333MHz
DDR2 PC2-6400 800MHz 400MHz
       
DDR PC2100 266Mhz 133MHz
DDR PC2700 333MHz 166MHz
DDR PC3200 400MHz 200MHz

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