Ddr2 Slot Color

1. You can put 1gb in each slot if they are the same. If not, you need to put the identical kits in the same color (blue 1gb/black 512mb, blue 1gb/black 512mb) To know what frequency your RAM is, you.
2. There are various RAM slots depending on the module. Let’s start from the beginning: SDRAM: This module had a 64-bit bus and needed 3.3V to work. What’s important is that it had 168 pins DIMM, so the SDRAM slot had 168 empty pin sockets. DDR1: The first double data rate memory had 184 pins. It was popular from the late 20th century to 2005.

Ddr2 and ddr3 Conclusion. DDR2 is the earlier version and is obsolete technology, also DDR3 is a later edition of this DDR in which DDR3 has been improved and provides more features like an increased storage area, very low power consumption, platform flexibility. Video: How to Identify RAM DDR1, DDR2, DDR3 and DDR4 from Motherboard Slots #170.

Double Data Rate 2 Synchronous Dynamic Random-Access Memory, officially abbreviated as DDR2 SDRAM, is a double data rate (DDR) synchronous dynamic random-access memory (SDRAM) interface. It superseded the original DDR SDRAM specification, and was itself superseded by DDR3 SDRAM (launched in 2007). DDR2 DIMMs are neither forward compatible with DDR3 nor backward compatible with DDR.

In addition to double pumping the data bus as in DDR SDRAM (transferring data on the rising and falling edges of the bus clock signal), DDR2 allows higher bus speed and requires lower power by running the internal clock at half the speed of the data bus. The two factors combine to produce a total of four data transfers per internal clock cycle.

Since the DDR2 internal clock runs at half the DDR external clock rate, DDR2 memory operating at the same external data bus clock rate as DDR results in DDR2 being able to provide the same bandwidth but with better latency. Alternatively, DDR2 memory operating at twice the external data bus clock rate as DDR may provide twice the bandwidth with the same latency. The best-rated DDR2 memory modules are at least twice as fast as the best-rated DDR memory modules.The maximum capacity on commercially available DDR2 DIMMs is 8GB, but chipset support and availability for those DIMMs is sparse and more common 2GB per DIMM are used.^{[citation needed][2]}

History[edit]

DDR2 SDRAM was first produced by Samsung in 2001. In 2003, the JEDEC standards organization presented Samsung with its Technical Recognition Award for the company's efforts in developing and standardizing DDR2.^[1]

DDR2 was officially introduced in the second quarter of 2003 at two initial clock rates: 200 MHz (referred to as PC2-3200) and 266 MHz (PC2-4200). Both performed worse than the original DDR specification due to higher latency, which made total access times longer. However, the original DDR technology tops out at a clock rate around 200 MHz (400 MT/s). Higher performance DDR chips exist, but JEDEC has stated that they will not be standardized. These chips are mostly standard DDR chips that have been tested and rated to be capable of operation at higher clock rates by the manufacturer. Such chips draw significantly more power than slower-clocked chips, but usually offered little or no improvement in real-world performance. DDR2 started to become competitive against the older DDR standard by the end of 2004, as modules with lower latencies became available.^[3]

Specification[edit]

Overview[edit]

The key difference between DDR2 and DDR SDRAM is the increase in prefetch length. In DDR SDRAM, the prefetch length was two bits for every bit in a word; whereas it is four bits in DDR2 SDRAM. During an access, four bits were read or written to or from a four-bit-deep prefetch queue. This queue received or transmitted its data over the data bus in two data bus clock cycles (each clock cycle transferred two bits of data). Increasing the prefetch length allowed DDR2 SDRAM to double the rate at which data could be transferred over the data bus without a corresponding doubling in the rate at which the DRAM array could be accessed. DDR2 SDRAM was designed with such a scheme to avoid an excessive increase in power consumption.

DDR2's bus frequency is boosted by electrical interface improvements, on-die termination, prefetch buffers and off-chip drivers. However, latency is greatly increased as a trade-off. The DDR2 prefetch buffer is four bits deep, whereas it is two bits deep for DDR. While DDR SDRAM has typical read latencies of between two and three bus cycles, DDR2 may have read latencies between three and nine cycles, although the typical range is between four and six. Thus, DDR2 memory must be operated at twice the data rate to achieve the same latency.

Another cost of the increased bandwidth is the requirement that the chips are packaged in a more expensive and difficult to assemble BGA package as compared to the TSSOP package of the previous memory generations such as DDR SDRAM and SDR SDRAM. This packaging change was necessary to maintain signal integrity at higher bus speeds.

Power savings are achieved primarily due to an improved manufacturing process through die shrinkage, resulting in a drop in operating voltage (1.8 V compared to DDR's 2.5 V). The lower memory clock frequency may also enable power reductions in applications that do not require the highest available data rates.

According to JEDEC^[4] the maximum recommended voltage is 1.9 volts and should be considered the absolute maximum when memory stability is an issue (such as in servers or other mission critical devices). In addition, JEDEC states that memory modules must withstand up to 2.3 volts before incurring permanent damage (although they may not actually function correctly at that level).

Chips and modules[edit]

For use in computers, DDR2 SDRAM is supplied in DIMMs with 240 pins and a single locating notch. Laptop DDR2 SO-DIMMs have 200 pins and often come identified by an additional S in their designation. DIMMs are identified by their peak transfer capacity (often called bandwidth).

* Some manufacturers label their DDR2 modules as PC2-4300, PC2-5400 or PC2-8600 instead of the respective names suggested by JEDEC. At least one manufacturer has reported this reflects successful testing at a higher-than-standard data rate^[8] whilst others simply round up for the name.

Note: DDR2-xxx denotes data transfer rate, and describes raw DDR chips, whereas PC2-xxxx denotes theoretical bandwidth (with the last two digits truncated), and is used to describe assembled DIMMs. Bandwidth is calculated by taking transfers per second and multiplying by eight. This is because DDR2 memory modules transfer data on a bus that is 64 data bits wide, and since a byte comprises 8 bits, this equates to 8 bytes of data per transfer.

In addition to bandwidth and capacity variants, modules can:

1. Optionally implement ECC, which is an extra data byte lane used for correcting minor errors and detecting major errors for better reliability. Modules with ECC are identified by an additional ECC in their designation. PC2-4200 ECC is a PC2-4200 module with ECC. An additional P can be added at the end of the designation, P standing for parity (ex : PC2-5300P).
2. Intel ® 6402 Advanced Memory Buffer
   Be 'registered' ('buffered'), which improves signal integrity (and hence potentially clock rates and physical slot capacity) by electrically buffering the signals at a cost of an extra clock of increased latency. Those modules are identified by an additional R in their designation, whereas non-registered (a.k.a. 'unbuffered') RAM may be identified by an additional U in the designation. PC2-4200R is a registered PC2-4200 module, PC2-4200R ECC is the same module but with additional ECC.
3. Be aware fully buffered modules, which are designated by F or FB do not have the same notch position as other classes. Fully buffered modules cannot be used with motherboards that are made for registered modules, and the different notch position physically prevents their insertion.

Note:

• Registered and un-buffered SDRAM generally cannot be mixed on the same channel.
• The highest-rated DDR2 modules in 2009 operate at 533 MHz (1066 MT/s), compared to the highest-rated DDR modules operating at 200 MHz (400 MT/s). At the same time, the CAS latency of 11.2 ns = 6 / (bus clock rate) for the best PC2-8500 modules is comparable to that of 10 ns = 4 / (bus clock rate) for the best PC-3200 modules.

Backward compatibility[edit]

DDR2 DIMMs are not backward compatible with DDR DIMMs. The notch on DDR2 DIMMs is in a different position from DDR DIMMs, and the pin density is higher than DDR DIMMs in desktops. DDR2 is a 240-pin module, DDR is a 184-pin module. Notebooks have 200-pin SO-DIMMs for DDR and DDR2; however, the notch on DDR2 modules is in a slightly different position than on DDR modules.

Higher-speed DDR2 DIMMs can be mixed with lower-speed DDR2 DIMMs, although the memory controller will operate all DIMMs at same speed as the lowest-speed DIMM present.

Relation to GDDR memory[edit]

GDDR2, a form of GDDR SDRAM, was developed by Samsung and introduced in July 2002.^[9] The first commercial product to claim using the 'DDR2' technology was the NvidiaGeForce FX 5800 graphics card. However, it is important to note that this GDDR2 memory used on graphics cards is not DDR2 per se, but rather an early midpoint between DDR and DDR2 technologies. Using 'DDR2' to refer to GDDR2 is a colloquialmisnomer. In particular, the performance-enhancing doubling of the I/O clock rate is missing. It had severe overheating issues due to the nominal DDR voltages. ATI has since designed the GDDR technology further into GDDR3, which is based on DDR2 SDRAM, though with several additions suited for graphics cards.

GDDR3 and GDDR5 is now commonly used in modern graphics cards and some tablet PCs. However, further confusion has been added to the mix with the appearance of budget and mid-range graphics cards which claim to use 'GDDR2'. These cards actually use standard DDR2 chips designed for use as main system memory although operating with higher latencies to achieve higher clockrates. These chips cannot achieve the clock rates of GDDR3 but are inexpensive and fast enough to be used as memory on mid-range cards.

See also[edit]

• CAS latency (definition of 'CAS 5-5-5-15', for example)

References[edit]

1. ^ ^ab'Samsung Demonstrates World's First DDR 3 Memory Prototype'. Phys.org. 17 February 2005. Retrieved 23 June 2019.
2. ^https://media-www.micron.com/-/media/client/global/documents/products/data-sheet/modules/parity_rdimm/htf36c256_512_1gx72pz.pdf?rev=e8e3928f09794d61809f92abf36bfb24
3. ^Ilya Gavrichenkov. 'DDR2 vs. DDR: Revenge gained'. X-bit Laboratories. Archived from the original on 2006-11-21.
4. ^JEDEC JESD 208 (section 5, tables 15 and 16)
5. ^Cycle time is the inverse of the I/O bus clock frequency; e.g., 1/(100 MHz) = 10 ns per clock cycle.
6. ^'DDR2 SDRAM SPECIFICATION'(PDF). JESD79-2E. JEDEC. April 2008: 78. Retrieved 2009-03-14.Cite journal requires journal= (help)
7. ^'SPECIALITY DDR2-1066 SDRAM'(PDF). JEDEC. November 2007: 70. Retrieved 2009-03-14.Cite journal requires journal= (help)
8. ^Mushkin PC2-5300 vs. Corsair PC2-5400
9. ^'Samsung Electronics Announces JEDEC-Compliant 256Mb GDDR2 for 3D Graphics'. Samsung Electronics. Samsung. 23 August 2003. Retrieved 26 June 2019.

Further reading[edit]

• JEDEC standard: DDR2 SDRAM Specification: JESD79-2F, November 2009 ** http://www.jedec.org/standards-documents/docs/jesd-79-2e
• JEDEC standard: DDR2-1066 **
• 'JEDEC Standard No. 21C: 4.20.13 240-Pin PC2-5300/PC2-6400 DDR2 SDRAM Unbuffered DIMM Design Specification' **
• JEDEC Solid State Technology Association
• Razak Mohammed Ali. 'DDR2 SDRAM interfaces for next-gen systems'(PDF). Electronic Engineering Times. Archived from the original(PDF) on 2007-09-26.

Note**: JEDEC website requires registration ($2,500 membership) for viewing or downloading of these documents: http://www.jedec.org/standards-documents

External links[edit]

Memory Channels

In the fields of digital electronics and computer hardware, multi-channel memory architecture is a technology that increases the data transfer rate between the DRAM memory and the memory controller by adding more channels of communication between them. Theoretically this multiplies the data rate by exactly the number of channels present. Dual-channel memory employs two channels.

Single-channel (asymmetric) mode
This mode provides single-channel bandwidth operations and is used when only one DIMM is installed or when the memory capacities of more than one DIMM are unequal. When using different speed DIMMs between channels, the slowest memory timing is also used.

Single Channel memory, with a maximum rated clock of 400 MHz and a 64-bit (8 bytes) data bus is now becoming obsolete and is not being produced in massive quantities. Technology is adopting new ways to achieve faster speeds/data rates for RAM memories.

Dual-channel architecture

Dual-channel-enabled memory controllers in a PC system architecture utilize two 64-bit data channels. Dual channel should not be confused with double data rate (DDR), in which data exchange happens twice per DRAM clock. The two technologies are independent of each other and many motherboards use both, by using DDR memory in a dual-channel configuration.

Dual-channel

architecture requires a dual-channel-capable motherboard and two or more DDR, DDR2 SDRAM, or DDR3 SDRAM memory modules. The memory modules are installed into matching banks, which are usually color-coded on the motherboard. These separate channels allow the memory controller access to each memory module. It is not required that identical modules be used (if motherboard supports it), but this is often recommended for best dual-channel operation.

Motherboards supporting dual-channel memory layouts typically have color-coded DIMM sockets. Coloring schemes are not standardized and have opposing meanings, depending on the motherboard manufacturer's intentions and actual motherboard design. Matching colors may either indicate that the sockets belong to the same channel (meaning that DIMM pairs should be installed to differently colored sockets), or they may be used to indicate that DIMM pairs should be installed to the same color (meaning that each socket of the same color belongs to a different channel). The motherboard's manual will provide an explanation of how to install memory for that particular unit. A matched pair of memory modules may usually be placed in the first bank of each channel, and a different-capacity pair of modules in the second bank.^[6]

Modules rated at different speeds can be run in dual-channel mode, although the motherboard will then run all memory modules at the speed of the slowest module. Some motherboards, however, have compatibility issues with certain brands or models of memory when attempting to use them in dual-channel mode. For this reason, it is generally advised to use identical pairs of memory modules, which is why most memory manufacturers now sell 'kits' of matched-pair DIMMs. Several motherboard manufacturers only support configurations where a 'matched pair' of modules are used. A matching pair needs to match in:

• Capacity (e.g. 1024 MiB). Certain Intel chipsets support different capacity chips in what they call Flex Mode: the capacity that can be matched is run in dual-channel, while the remainder runs in single-channel.
• Speed (e.g. PC5300). If speed is not the same, the lower speed of the two modules will be used. Likewise, the higher latency of the two modules will be used.
• Same CAS Latency (CL) or Column Address Strobe.
• Number of chips and sides (e.g. two sides with four chips on each side).
• Matching size of rows and columns.

Dual-channel architecture is a technology implemented on motherboards by the motherboard manufacturer and does not apply to memory modules. Theoretically any matched pair of memory modules may be used in either single- or dual-channel operation, provided the motherboard supports this architecture.

Performance

Theoretically, dual-channel configurations double the memory bandwidth when compared to single-channel configurations. This should not be confused with double data rate (DDR) memory, which doubles the usage of DRAM bus by transferring data both on the rising and falling edges of the memory bus clock signals.

Tom's Hardware found little significant difference between single-channel and dual-channel configurations in synthetic and gaming benchmarks (using a 'modern (2007)' system setup). In its tests, dual channel gave at best a 5% speed increase in memory-intensive tasks.^[7] Another comparison by Laptop logic resulted in a similar conclusion for integrated graphics.^[8] The test results published by Tom's Hardware had a discrete graphics comparison.

Another benchmark performed by TweakTown, using SiSoftware Sandra, measured around 70% increase in performance of a quadruple-channel configuration, when compared to a dual-channel configuration.^{[9]:p. 5} Other tests performed by TweakTown on the same subject shown no significant differences in performance, leading to a conclusion that not all benchmark software is up to the task of exploiting increased parallelism offered by the multi-channel memory configurations.^{[9]:p. 6}

Ganged versus unganged

Dual-channel was originally conceived as a way to maximize memory throughput by combining two 64-bit buses into a single 128-bit bus. This is retrospectively called the 'ganged' mode. However, due to lackluster performance gains in consumer applications,^[10] more modern implementations of dual-channel use the 'unganged' mode by default, which maintains two 64-bit memory buses but allows independent access to each channel, in support of multithreading with multi-core processors.^[11][12]

'Ganged' versus 'unganged' difference could also be envisioned as an analogy with the way RAID 0 works, when compared to JBOD.^[13] With RAID 0 (which equals to 'ganged' mode), it is up to the additional logic layer to provide better (ideally even) usage of all available hardware units (storage devices, or memory modules) and increased overall performance. On the other hand, with JBOD (which equals to 'unganged' mode) it is relied on the statistical usage patterns to ensure increased overall performance through even usage of all available hardware units.^[11][12]

Triple-channel architecture

Operation

DDR3 triple-channel architecture is used in the IntelCore i7-900 series (the Intel Core i7-800 series only support up to dual-channel). The LGA 1366 platform (e.g. Intel X58) supports DDR3 triple-channel, normally 1333 and 1600Mhz, but can run at higher clock speeds on certain motherboards. AMD Socket AM3 processors do not use the DDR3 triple-channel architecture but instead use dual-channel DDR3 memory. The same applies to the Intel Core i3, Core i5 and Core i7-800 series, which are used on the LGA 1156 platforms (e.g., Intel P55). According to Intel, a Core i7 with DDR3 operating at 1066 MHz will offer peak data transfer rates of 25.6 GB/s when operating in triple-channel interleaved mode. This, Intel claims, leads to faster system performance as well as higher performance per watt.^[14]

When operating in triple-channel mode, memory latency is reduced due to interleaving, meaning that each module is accessed sequentially for smaller bits of data rather than completely filling up one module before accessing the next one. Data is spread amongst the modules in an alternating pattern, potentially tripling available memory bandwidth for the same amount of data, as opposed to storing it all on one module.

The architecture can only be used when all three, or a multiple of three, memory modules are identical in capacity and speed, and are placed in three-channel slots. When two memory modules are installed, the architecture will operate in dual-channel architecture mode.^[15]

One of the differences between DDR, DDR2 and DDR3 is the highest transfer rate each generation can reach. Below is a list the most common speeds for each generation.

DDR memory's primary advantage is the ability to fetch data onboth the rising and falling edge of a clock cycle, doubling thedata rate for a given clock frequency. For example, in a DDR200device the data transfer frequency is 200 MHz, but the busspeed is 100 MHz.

DDR1, DDR2 and DDR3 memories are powered up with 2.5,1.8 and 1.5V supply voltages respectively, thus producing lessheat and providing more efficiency in power management thannormal SDRAM chipsets, which use 3.3V.

Temporization is another characteristic of DDR memories.Memory temporization is given through a series of numbers,such as 2-3-2-6-T1, 3-4-4-8 or 2-2-2-5 for DDR1. Thesenumbers indicate the number of clock pulses that it takes thememory to perform a certain operation—the smaller the number,the faster the memory.

The operations that these numbers represent are the following:CL–tRCD–tRP–tRAS–CMD. To understand them, you haveto keep in mind that the memory is internally organized as amatrix, where the data is stored at the intersection of the rowsand columns.

• CL: Column address strobe (CAS) latency is the time it takes between the processor asking memory for data and memory returning it.
• tRCD: Row address strobe (RAS) to CAS delay is the time it takes between the activation of the row (RAS) and the column (CAS) where data is stored in the matrix.
• tRP: RAS precharge is the time between disabling the access to a row of data and the beginning of the access to another row of data.
• tRAS: Active to precharge delay is how long the memory has to wait until the next access to memory can be initiated.
• CMD: Command rate is the time between the memory chip activation and when the first command may be sent to the memory. Sometimes this value is not informed. It usually is T1 (1 clock speed) or T2 (2 clock speeds).

Single Vs Double Sided ram

In SDRAM single sided (high density) can be used only in modern PCs. Old PCs don't always read the memory right because they calculate how much RAM to access based on the number of chips on the stick, not taking into account that each chip might contain twice the storage.
So for old PCs you should use double-sided (low density) RAM to ensure that it will work correctly in your system. Otherwise, the PC might end up convinced that your memory has only half the storage capacity that it is actually capable of.
To my knowledge, in SDRAM there is no real performance difference between the two. (Unlike with RDRAM which increases latency by the number of chips, so high-density is slightly faster than low-density.) So any modern PC that can properly use the single-sided (high density) SDRAM should be happy with whatever combination that you use.

Several types of memory modes can be configured on Intel® Desktop Boards, depending on how many memory modules (DIMMs) are installed:

Single-channel (asymmetric) mode
This mode provides single-channel bandwidth operations and is used when only one DIMM is installed or when the memory capacities of more than one DIMM are unequal. When using different speed DIMMs between channels, the slowest memory timing is also used.

Single-channel with one DIMM

Single-channel with three DIMMs

At boot, the memory configuration is detected and you might see this alert message:

Alert: Maximum memory performance is achieved with equal amounts of memory installed in each channel. Press any key to continue.

With the DIMMs that are currently installed, the computer is set to single-channel mode, but it can be set to dual-channel mode. If you shut down and rearrange the DIMMs properly, you can establish dual-channel mode.

Dual-channel (interleaved) mode
This mode offers higher memory throughput and is enabled when the memory capacities of both DIMM channels are equal. When using different speed DIMMs, the slowest memory timing is used.

Dual-channel with two DIMMs

Dual-channel with three DIMMs

Dual-channel with four DIMMs

Rules to enable dual-channel mode
To achieve dual-channel mode, the following conditions must be met:

• Same memory size. Examples: 1 GB, 2 GB, 4 GB.
• Matched DIMM configuration in each channel
• Matched in symmetrical memory slots

Configurations that do not match the above conditions revert to single-channel mode. The following conditions do not need to be met:

• Same brand
• Same timing specifications
• Same speed (MHz)

The slowest DIMM module populated in the system decides memory channel speed.

Triple-channel mode
Triple-channel interleaving reduces overall memory latency by accessing the DIMM memory sequentially. Data is spread through the memory modules in an alternating pattern.

Three independent memory channels give two possible modes of interleaving:

• Triple-channel mode is enabled when identical matched memory modules are installed in each of the three blue memory slots.
• If only two of the blue memory slots are populated with matched DIMMs, dual-channel mode is enabled.

Quad-channel mode
This mode is enabled when four (or a multiple of four) DIMMs are identical in capacity and speed, and are put in quad-channel slots. When two memory modules are installed, the system operates in dual-channel mode. When three memory modules are installed, the system operates in triple-channel mode.

Ddr2 Slot Colors

Quad-channel with four DIMMs:

Ddr2 Slot Colorado Springs

Quad-channel with eight DIMMs:

Ddr2 Slot Coloring Pages

Flex mode
This mode results in both dual and single-channel operation across the whole of DRAM memory. The figure shows a flex mode configuration using two DIMMs. The operation is as follows:

Ddr2 Slot Colorado

• The 2 GB DIMM in slot 1 and the lower 2 GB of the DIMM in slot 2 operate together in dual-channel mode.
• The remaining (upper) 2 GB of the DIMM in slot 2 operates in single-channel mode.