Kingston Technology memory ranking technical brief
吃的成语Memory ranks and Intel E7320 / E7520 chipt bad rvers April 2005
Kingston Technology memory ranking technical brief – 1
Introduction
The processors, chipts and memory controllers ud by system manufacturers are constantly developing and changing. New developments have led to a technology known as memory ranks becoming an important consideration when choosing rver system memory. This technical brief explains what memory ranks are, and details their relevance and importance within a rver system. Whilst the concept of memory ranks can apply to all memory module form-factors, such as desktop DIMMs, notebook SODIMMs, and workstation and rver Registered DIMMs; in general, it is only currently relevant to rver platforms due to their higher memory capacity and motherboard chipts.
Definition of a rank
The term “rank” was created and defined by JEDEC, the memory industry standards group. A memory rank is simply a unique, independently addressable 64-bit data area of a memory module. Each rank m
人事行政助理ust be 64-bits wide except on memory modules that support Error Correction Code (ECC), where the 64-bit wide data area requires an 8-bit wide ECC area for a total width of 72-bits. Depending on how a DIMM is manufactured, and which DRAM chips are ud in its construction, a single memory module could compri 1, 2 or 4 ranks making it a single, dual or quad rank module. It is important to note that a single rank DIMM or dual rank DIMM are different from a single-sided or double-sided DIMM.
A rank can apply to:
• The whole module (either single or double sided) This is known as a single rank module • Each side of a double-sided module This is known as a dual rank module • Multiple ranks within a double-sided module This is known as a quad rank module
全校通报Figure 1 - How ranks can be applied to a memory module
接地线
煤质化验As a rule, single-sided modules are always single-ranked. Doubled-sided unbuffered DIMMs and SODIMMs are always dual-ranked. Registered DIMMs, ud for rvers and workstations, vary from single to four ranks, as illustrated in Figure 1 above.
Why ranks are important
Although memory ranks are not a new technology, with the advent of the latest motherboard chipts, they have become an important factor in deciding which memory to populate a rver system with. Selecting the wrong memory could result in a reduction in the total capacity of the rver system and could create problems for future upgrading.
Servers bad upon Intel’s E7320 and E7520 chipts (codenamed “Lindenhurst”) limit the number of memory ranks of DDR or DDR2 memory. This means that the combined number of memory
ranks for all the memory modules must not exceed the maximum number. If the number of memory ranks exceeds the specified maximum ranks t by the chipt, the rver may not boot or may not operate reliably.
The number of ranks is important bad upon the rver’s memory speed:
• If PC2100 memory is ud, the number of ranks is not critical and either single or dual rank memory module pairs can be ud.
• If PC2700 or PC2-3200 memory is ud, there is typically a maximum of 8 ranks per rver.
o If two pairs of 2GB dual-ranked memory modules are inrted into the memory sockets, that would add up to 8 ranks (4 modules x 2-ranks each = 8 ranks = 8GB
capacity); in this ca, the remaining four empty memory sockets cannot be ud
for future upgrading.
o If four pairs of 2GB single ranked modules are inrted into the memory sockets, that would also add up to 8 ranks (8 modules x 1 rank each = 8 ranks); but in this
ca the total rver capacity would be 16GB.
It is fair to point out that single and dual ranked memory modules do vary in price. This is directly rel
ated to how the modules are manufactured. In general, single-ranked memory modules are built using x4 (“By 4”) DRAM chips and can be more expensive than most dual-rank memory modules (which are typically built using x8 DRAM chips). Dual-ranked memory modules can cost less but may limit future upgradeability and capacity of rvers using PC2700 or PC2-3200 memory. This trade-off between cost and capacity is important to consider when purchasing memory modules for Intel Lindenhurst-bad rvers.
最小公倍数的定义The u of x4 modules can bring additional benefits. Modules bad upon x4 DRAMs will allow you to access the latest chipt and motherboard features such as;
• Intel’s Single Device Data Correction (SDDC)
• Memory scrubbing
• DIMM sparing
• DIMM mirroring
• And so on…
英语祈使句>向日葵的精神
x8 DRAMs do not support the latest features. Again, different systems manufacturers may choo to implement different features, and not all vendors will offer all available features.
Memory ranks best practice
The implementation of ranks can differ from one system vendor to another. Some vendors may enable their rvers to work with single rank modules only; others may enable their systems to work with both single and dual rank modules. A rver that has been configured with the wrong memory may work at sub-standard performance or may not boot or work properly. It is important to ensure that the correct memory modules are installed in accordance with the original systems manufacturers instructions. Some systems will allow the mixing of single and dual rank modules, others will not. Some may allow modules to be installed as singles; many others will only allow modules to be installed in pairs or kits.
Kingston Technology suggests the following best practice guidelines:
• U identical matched pairs (module kits) as per Figure 2 below
• U x4 modules so that the latest rver features can be supported
• Do not mix single and dual modules – this will affect performance
• Always check your requirements against our online memory configurator –
/europe/config to check individual system specifications and the type of memory supported
Figure 2 - Dos and Don'ts for module pairs
As mentioned previously, different system vendors can apply different configurations to their rvers, but as a general rule, x4 and x8 modules cannot be mixed within a pair of modules; in addition, you cannot mix x4 single-rank memory modules with x4 dual-rank memory modules. Plea check the online Kingston Technology memory configurator
/europe/config to verify your rvers’ configuration details.
Quad-rank memory modules
Quad-ranked memory modules require special motherboard modifications and an enabled rver BIOS to work properly. Unless a rver or system board is specifically designed to support quad-rank memory modules, they will not work. It is expected that only a limited number of rver motherboards will support quad-rank memory modules during 2005. When quad-rank memory modules are supported, rver boards will only be able to accommodate 2 quad-ranked memory modules as the 8-rank maximum will be reached, making them ideal for rvers with a limited number of memory sockets.
Summary
Single rank memory modules will allow a rver to reach its maximum memory capacity and highest performance levels, whilst enabling support for the latest rver chipt and motherboard features – dependant on system manufacturers’ specifications.
Dual rank modules can be ud if a system vendor allows it. The modules offer a keen
price/performance point but can limit overall system capacity, restrict future upgrade options and will typically not support the latest chipt and motherboard features.
If you have any comments or questions about this brief, plea email eu_ or visit our dedicated rver memory zone /europe/rver
© 2005 Kingston Technology Europe Ltd, Kingston Court, Brooklands Clo, Sunbury-on-Thames, Middlex, TW16 7EP, England. Tel: +44 (0) 1932 738888 Fax: +44 (0) 1932 738811 All rights rerv
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