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FAQ

This page contain answers to common questions asked about memory module technology. The information provided may help you build a better undersanding about DRAM memory subsystems.

FAQ                                                                                   Answer                                                                                  
What DRAM configuration provides the lowest power at highest density? DRAM that operates at the both the lowest voltage and the lowest speeds often have the lowest power consumption. Currently, DDR3 operates at the lowest voltage at 1.5 volts.
What is the standard operating temperature range for a DDR2 SO-DIMM? DDR2 DRAM are specified at 0-85C (case temperature)
If industrial temperature (extended temperature) DRAMs are not available, What other options are there? See the technical notes on Thermal Options (for Modules)
What is the maximum speed for DDR2 JEDEC standard for DDR2 is 400Mhz clock frequency with a 800Mhz data rate.
What is a the typical power consumption for a 4G SODIMM The answer is based on a calculation. See the technical notes for Power Consumption (for Modules)
What is the highest density available for a 4 rank RDIMM using 2Gbit DRAM? 16GB modules
Are the SO-CDIMM and SO-RDIMM custom or JEDEC-standard? SO-CDIMM and SO-RDIMM will be JEDEC-standard in late 2007
Is using a thermal sensor on a DIMM custom or JEDEC-standard? Certain DDR2 JEDEC modules are specified with a thermal sensor. DDR3 is specified with thermal sensors within the DRAM.
What is MB and why is it different than Mb MB is shorthand for MegaByte. Mb is shorthand for Megabit. Megabyte often defines memory module density. Megabit often defines DRAM memory chip density.
What is GB and why is it different than Gb GB is shorthand for GigaByte. Mb is shorthand for Gigabit. Gigabyte often defines memory module density. Gigabit often defines DRAM memory chip density.
What are the difference between Intel and AMD on DDR2 RDIMM support? Read the technical notes on Chipsets
What is RAMpedia? RAMpedia is a memory resource for design engineers. It is an informational website and technical engineering database that is hosted by Virtium Technology, to specifically address DRAM memory technology. It's purpose is to help computer board designers enhance their knowledge of DRAM memory modules and how to use them in DRAM memory subsystems.
What is the difference between a rank and a bank? A Bank is a collective group of memory cells inside a memory chip. A rank is a group of DRAMs that are tied to a single, unique chip select. Note that there is a distinction between rank (for a memory module) and bank (for a DRAM). The number of chip selects on the memory controller will determine the number of memory ranks it can support. DIMMs that have a single chip select are called 1-rank (one rank or single rank). DIMMs can have multiple chip selects, DIMMs that have two chip selects are called 2-rank (two rank or dual rank) and DIMMs that have 4 chip selects are called 4-rank (four rank or quad rank)
What is quad rank (or 4-rank) DIMMs that have 4 chip selects are called 4-rank (four rank or quad rank)
What is difference between 1T and 2T addressing (or Timing) for DDR1 and DDR2 Addressing Modes DDR1 and DDR2 generally use the “1T addressing” mode which allows a new memory command every clock rising-edge. However, when the system memory controller cannot drive a memory command on every clock rising edge because the capacitive loading on the address bus is too high, then 2T addressing (or “2N addressing”) may be needed.
What is the difference between stacked and planer memory a planer memory module uses monolithic chips that are not chip stacked. A chip stacked module uses 2 or more monolithic chips placed on top of each other (sometimes called PoP or Package-on-Package). A Board Stack modudle uses 2 or more memory modules assembled on top of each other in a stacked arrangement (ie microDIMM) (a.k.a. Board on Board)