Memory spec terms
If you're not sure if a module is right for your system, use the Crucial Memory Advisor tool for a list of guaranteed compatible modules.
NON-ECC/Non-parity Most desktop and laptop computers take NON-ECC or Non-parity memory.
ECC/Parity ECC or parity modules look for errors in data and are most often found in servers and other mission-critical applications used by large networks and businesses.
Unbuffered Most PCs and workstations use unbuffered memory which is faster than registered memory.
Registered/Buffered Registered or buffered modules delay all information transferred to the module by one clock cycle. This type of memory is primarily used in servers.
Fully buffered Designed for next-generation servers, features an advanced memory buffer.
CL CAS (column address strobe) latency, which is the number of clock cycles it takes before data starts to flow after a command is received. Lower CL is faster. Modules with different CL can be mixed on a system, but the system will only run at the highest (slowest) CL.
Component configuration (For example: 64Meg x 64) Indicates the size of the memory chip components on the module.
Voltage For example 2.6V. Indicates the power used by the module. The lower the better.
Approximately 5.25 in. by 1.18 in. (133.35 mm by 30 mm)A dual inline memory module (DIMM) consists of a number of memory components (usually black) that are attached to a printed circuit board (usually green). The gold pins on the bottom of the DIMM provide a connection between the module and a socket on a larger printed circuit board. The pins on the front and back of a DIMM are not connected to each other.240-pin DIMMs are used to provide DDR2 SDRAM memory for desktop computers. DDR2 is a leading-edge generation of memory with an improved architecture that allows it to transmit data very fast.Each 240-pin DIMM provides a 64-bit data path (72-bit for ECC or registered or Fully Buffered modules). (The Ballistix™ and Ballistix Tracer™ high-performance memory do not come in 72-bit or registered modules.)Standard DDR2 240-pin DIMMs are available in DDR2 PC2-3200 SDRAM, DDR2 PC2-4200 SDRAM, DDR2 PC2-5300 SDRAM, and PC2-6400 SDRAM.To use DDR2 memory, your system motherboard must have 240-pin DIMM slots and a DDR2-enabled chipset. A DDR2 SDRAM DIMM will not fit into a standard SDRAM DIMM socket or a DDR DIMM socket.The number of black components on a 240-pin DIMM can vary, but it always has 120 pins on the front and 120 pins on the back, for a total of 240. 240-pin DIMMs are approximately 5.25 inches long and 1.18 inches high, though the heights can vary. While 240-pin DDR2 DIMMs, 184-pin DDR DIMMs, and 168-pin DIMMs are approximately the same size, 240-pin DIMMs and 184-pin DIMMs have only one notch within the row of pins. The notch in a 240-pin DDR2 DIMM is closer toward the center of the module.Ballistix and Ballistix Tracer 240-pin DIMMsOur high-performance Ballistix 240-pin DIMMs come in DDR2 PC2-5300 SDRAM, DDR2 PC2-6400 SDRAM, and DDR2 PC2-8000 SDRAM. The Ballistix Tracer illuminated, activity-indicating high-performance 240-pin DIMM comes in SDRAM, DDR2 PC2-6400 SDRAM, and DDR2 PC2-8000 SDRAMFor more information about the Ballistix memory line, please visit the Ballistix section of our Web site.Ballistix 240-pin DIMM Approximately 5.25 in. by 1.18 in. (133.35 mm by 30 mm)Ballistix Tracer 240-pin DIMM Approximately 5.25 in. by 1.18 in. (133.35 mm by 30 mm)
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I have a Dell Dimension 8400. I want to take out the memory and add 3GB of higher speed memory. These Crucial 1GB modules seem to have the same specs as memory which Dell says is compatible with my 8400. Yet Crucial's Memory Advisor says this module is not compatible. Is this correct?
PC2-4200 (DDR2-533), PC2-5300 (DDR2-667), PC2-6400 (DDR2-800), and PC2-8500 (DDR2-1066) memory are all types of Double Data Rate, second-generation SDRAM, usually referred to as DDR2. The varying numbers refer to the different speeds of memory your computer was designed for. PC2-6400 (DDR2-800), which has a bandwidth of 6.4GB/sec and is designed for use in systems and motherboards that require a 400MHz front-side bus, with an effective front-side bus speed of 800MHz.
Answered on 5/3/2011 by Crucial Support from Meridian, Idaho
Its referring to the speed of the ram itself in technical terms mostly labeled on the packaging of the item. A dimm module for example a 2gb 800mhz 240 pin PC2-6400 is clocked at 800mhz so the 800mhz is multiplied by 8 bit (smallest digital character) which equals 6400(800x8=6400), same thing goes for a dimm(ram) which is clocked at 667mhz then this would be 667x8=5336 but on the box of the ram you'll see PC2-5300.
Answered on 10/3/2011 by vaina001 from Jersey City, NJ
The 6400 is basically the speed that the RAM runs at. Not sure what the speed is measured by (GHz or MB ect) but naturally the higher the better, however, if you are installing more RAM into a computer then the RAM will only go as fast as the slowest RAM already installed.