Double Data Rate 3 Synchronous Dynamic Random-Access Memory, commonly known as DDR3, has been prevalent in the market since 2007.
It possesses much higher bandwidth and speed compared to the previous versions of DDR1 AND DDR2.
DDR3 is not forward compatible nor is it backward compatible with any kind of RAM belonging to the previous generations.
It is because DDR3 works based on different signaling voltages and clock timing and frequency factors.
The primary benefit of DDR3 over its earlier versions is the capability for the transfer of data at twice the rate which is about eight times that of its internal memory arrays.
This enables higher bandwidth and accurate transfer concerning data and information.
Double Data Rate 4 Synchronous Dynamic Random-Access Memory is abbreviated as DDR4.
It is one of the most-latest variants of RAM with much higher speed factors than DDR3.
It is not very compatible with any of the earlier versions of RAM due to different physical interfaces.
This is also a type of synchronous memory with a high bandwidth interface, using the “double data rate”.
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The primary advantage of DDR4 over any other type of RAM is its high modular density and the requirement of comparatively low voltage.
DDR4 operates at a power voltage of about 1.2V.
The frequency can range from 800MHz to about 1600 MHz in a typical system.
The density ranges from 2-16 GB.
These higher-density devices enable the users to take sure-shot advantage of the memory space.
More availability of memory spaces also relates to more number of placement cells in the memory allocation unit.
This, in turn, can help to reduce the general costs for each of the components of RAM.
DDR3 Vs DDR4: Morphological Differences
The first difference which can be noticed in the physical layout of DDR3 and DDR4 is with regard to the number of pin connections.
DDR3 RAM typically uses a 240-pin connector. On the other hand, DDR4 uses a 288-pin connector.
This difference in the physical design ensures that no one accidentally inserts the wrong type of RAM in their motherboard.
This prevents any further damage to the motherboard which would have been caused if both the RAMs would fit into the specified location in the motherboard.
Also, DDR3L is another variant of DDR3 that looks the same as DDR3.
The only difference is that it can work on both 1.5 as well as 1.35 V while DDR3 can only work with 1.5 V.
Internal Specifications
DDR3’s clock speed frequency can vary from 80MHz to about 2133 MHz which is its peak value.
In normal terms, the average clock frequency can be specified to e between 1600MHz and 1800MHz.
DDR3 automatically performs self-refresh as well as auto-refresh to refresh the contents of the RAM.
Self-refresh is specifically very useful because it leads to much lower power consumption in comparison to DDR2 or any other previous versions.
The cost of DDR3 is lower as compared to DDR4. DDR3 consumes less power in comparison to DDR2 but more power as compared to DDR4.
It has 16 GB of memory capacity. It has lower latency when it is compared to DDR4.
DDR4 only provides the option of self-refresh.
The minimum clock speed or frequency of DDR4 can be around 2133 MHz and can ultimately have no defined maximum clock frequency and adjusts itself as per the user’s requirement.
The cost of DDR4 is higher as compared to DDR3. But, DDR4 consumes much less power in comparison to DDR3.
It has unlimited memory capability or capacity. It has a slightly increased latency than DDR3.
Memory Modules
Dual In-Line Memory Module is another type of computer memory. It is mainly installed in the motherboard’s memory slots in the computer system.
Single In-Line Memory Module is the earlier version of the Dual In-Line Memory Module.
A single In-Line Memory Module needs to be installed in matching pairs.
This significantly helps in achieving a memory-data path of 64 bits.
This can successfully enable a single “Dual In-Line Memory Module” to transfer the data twice as fast as a single “Single In-Line Memory Module”.
A dual In-Line Memory Module is the most common type of memory allocation mechanism used.
A dual In-Line Memory Module can be installed on a motherboard and can store each of the bits of data and information in a separate allocated memory location.
The dual inline memory module system of DDR3 has 240 pins.
These pins are electrically not compatible due to the different structures of DDR3.
There is also a key notch that helps to avoid accidental interchangeability. DDR2 and DDR3 are, concerning technological considerations, keyed differently.
DDR2 has rounded notches on the side whereas DDR4 has square notches.
Intel has designed a package which is named UniDIMM. It can use either DDR3 modules or DDR4 modules.
CPU’s integrated memory system can work with both of them.
This serves a very important purpose as far as industrial use is concerned.
It can make a transition between DDR3 and DDR4 simpler where pricing can make it desirable to switch between different types of RAM in the computer system.
On the other hand, Modern Dual In-Line Memory Module is based on DDR4 chips.
These chips use 288-pin connectors as opposed to the 240 pins used in DDR3.
The higher number of pin connectors enables the increase in data and information throughput.
The pins in DDR4 are of the same size as that of DDR3.
However, the pins are spaced much more compactly to fit the increased number of pin connections in the same five-and-a-half-inch (135.35 mm) standard Dual In-Line Memory Module length.
The height of the pins is slightly increased from 30.35 mm or 102 inches to 31025mm or 1023 inches.
This tremendously helps to make signal routing easier.
The thickness of the pins is increased from 1.0 mm to 1.2 mm. This will help to accommodate more signal layers during processing.
DDR4 modules are programmed such that all of the pins are not engaged during module insertion, which in turn can lower the insertion force.
Therefore, they have a curved edge connecting mechanism. They are spaced at 0.5 mm instead of 0.6 m, like in the case of earlier versions.
This makes DDR4 a better option to choose, as compared to DDR3
External Design
DDR3 has one of the significant features in terms of commercial usage.
The flyby architecture is an additional quality that reduces simultaneous switching noise by the deliberate grouping of the main data groups.
Improved device pin-out along with dynamic ODT for improved write-signaling makes DDR3 user-friendly.
It also reduces power consumption to a considerable extent along with improved device pin-out Driver calibration, device reset, and Dual In-Line Memory Module address mirroring making DDR3 very easy to use.
Micron Technology has added some of the key points for the Integrated Circuit Design of DDR4. DDR4 requires VrefDQ calibration.
These functions are generally performed by the controller. This has been introduced in DDR4.
New addressing schemes including “bank grouping”, CAS and WE commands have also been introduced.
PAR and Alert are important functions that have been introduced for error checking. DBI mechanism assists in data bus inversion.
DDR4 is also acquirable with power-saving features like temperature-controlled refresh and fine-granularity refresh.
Low-power auto self-refresh is also an amazing added feature in DDR4.
Circuit Board Design
DDR3 has an asynchronous reset pin and supports system-level flight-time compensation.
These are the main features that distinguish DDR3 from its previous versions.
DDR3 also provides CWL which refers to CAS write latency per clock bin.
Accurate READ/WRITE calibrations are specifically designed onto circuit boards.
Dynamic ODT (On-Die-Termination) is the exclusive feature that allows different terminatory values to be allocated for various kinds of logical operations like READ/WRITE operations.
The high-precision calibration resistors coupled with the fly-by command control bus are technological advancements.
However, the DDR3 modus does not fit into DDR2 sockets, and if forced, it can permanently damage the motherboard.
It also provides slightly improved latencies if measured in nanoseconds.
It provides superior performance as compared to other RAM types even at low power.
DDR4 provides new power supplies including VDD/VDDQ at 1.2 volts along with a word line boost.
DQ pins also terminate high in the case of DDR4.
This uses pseudo-open-drain I/O, which differs significantly from CA pins in DDR3.
The pins are center-tapped to VTT in a typical DDR3 design, which is not in the case with DDR4 designs.
Similarly, VrefDQ is supplied internally to the dynamic RAM. On the other hand, VrefCA has to be supplied externally from the circuit board.
It uses Rowhammer Mitigation Techniques which in turn larger storage capacitors.
This can help in modifying the usage of address space layout randomization.
Another added feature in DDR4 is dual voltage I/O LINES.
This further isolates any potential conditions which in rare cases, can lead to instability within the system.
Variants and Extensions
ECC memory is a module within DDR3 that consists of an extra byte data lane. This helps in correcting as well as detecting any errors.
Modules that include ECC are identified by an additional mechanism called ECC or E. This can be understood by their designation.
At the same time, registered or buffered memory greatly improves signal integrity and potential clock rates, and slot capacity.
These modules are usually identified with an R in their respective designation.
DR3 modules can also be non-registered ERAM which are identified by an additional designation, denoted by the U symbol.
Load-reduced modules are designated by LR.
They are in many terms similar to buffered or registered memory systems because both of them retain the parallel strength of the signals even while buffering both controls as well as data lines.
However, modules that are fully buffered can never be used with a motherboard.
Such buffered modules are designated in the market by F or FB.
Both fully buffered as well as load-reduced memory types within DDR3 are given an important action to control the amount of electricity that passes from a particular memory location or a memory chip at any given point in time.
DDR4 is often described with the involvement of a 30 nm process at 1.2 volts.
Its variants usually possess bus frequencies of 2133 MT/s which is termed a “regular” speed.
Its additional feature consists of 3200 MT/s which is known as “enthusiast” speed.
Samsung validated 40 nm dynamic RAM chips and invested significantly in their development.
Consequently, huge productions of DDR4 were initiated after DDR4 test samples were announced in line with earlier production.
Thus, the maximum data transfer rate of 2133MT/s at 1.2 V became a major feature.
It uses pseudo-open-drain technology and draws a lot of lesser power than the equivalent DDR3 modules.
There are also semiconductor processes that transition DDR4 to sub-430 nm.
The highest density 128 GiB module based on 20 nm technology works at 2133 MHz with a 64-bit I/O process system. It could process data at a rate of about 17 GB per second.
Further, DDR4 could also support 3200 megabits per second rate of transfer with further technological advancement.
It means that DDR4 provides a 30% faster rate of transfer of data and information as compared to DDR3.
Data bus
DDR3 consists of ADDR/CMD/CNTL buses in a point-to-point system.
When terminating these buses, there are a variety of options available.
Tree with VTT R, the tree with series R, and fly-by options is the option.
A tree with a VTT R option has many advantages. It can provide the best signal among all the available options.
Therefore, the point-to-point mechanism system can be destroyed.
A tree with series R helps the user to manipulate the problem when any error arises between the driver and the transmission line.
It also does not require any additional VTT power.
The fly-by option provides ease to the user with regard to the induction of skew between the main buses of the computer system, mainly the data bus and the clock bus.
The best termination technique for buses within the computer system depends greatly on the design requirements.
DDR4 operates on a high frequency in comparison with DDR3.
Therefore, the improvements in the controller of DDR4 are reduced skew and additional adjustment and training features.
There are mainly two options for command as well as address bus.
However, both of them have advantages as well as disadvantages regarding different aspects of their work.
Routing is much easier in the case of the Daisy Chain bus. But, it is difficult if the Tree Bus is considered.
The tree bus has excellent performance as far as DDR4 is considered, but it offers lower bandwidth.
At the same time, the daisy chain bus offers higher bandwidth and the performance level is also good.
Tree buses are difficult to handle and are very sensitive to large loads.
They can easily get damaged if not taken care of properly.
The daisy chain buses are comparatively easier to handle and are unaffected by large loads.
This means that it can undergo pressure in terms of data load.
When timing skews are considered, the tree bus has minimal issues.
Daisy chain buses can give issues that can require leveling to be dealt with.
Memory Architecture
In the case of DDR3, the memory architecture is assumed to be an asymmetrical layout, specifically concerning tree layout.
It also has added minimal clock skews between command, address and control, and data buses.
The DDR3 memory system can have the architecture to be a daisy-chain layout or fly-by architecture type.
However, in the case of point-to-point designs, fly-by architecture is not required to be implemented. This is because fly-by architecture requires primary timing skew between two important buses, namely the clock and data buses.
Also, the command, data, and address buses would then require termination.
However, it is always suitable for the user to hard code the skews rather than having to use secondary features including write-leveling features.
In the case of DDR4, the device uses a kind of pre-fetch called the 8-n pre-fetch architecture to achieve high-speed performance and efficiency.
Any READ/WRITE operation consists of a four-clock data transfer and internal dynamic RAM.
Along with this, it also includes two corresponding n-bit wide and one half-clock cycle data and information transfer at I/O pins.
The clock rate (maximum) and data transfer rate (minimum) are the essential operating conditions with the DLL-enabled or normal operating systems.
What Is RAM Actually and What it does Do for Your PC?
RAM stands for Random Access Memory.
It is the hardware component in the computing device where the operating system (OS), programs, and data that are regularly used are kept.
This assists the user in quick and easy access to a specified memory block. Computer memory systems can broadly be classified into two memory types, RAM and ROM.
RAM is the volatile memory, which essentially means a temporary memory storage location whereas ROM is non-volatile, meaning the permanent type of memory.
Volatile memory refers to temporary storage and random access to the memory block.
RAM is extensively used in servers, tablets, smartphones, PCs, and other similar application devices, such as printers.
Besides that, RAM is much faster to read and write as compared to a hard disk drive (HDD) or any kind of solid-state drive (SSD).
Types of RAM
RAM can generally be classified into two main types:
Dynamic RAM (DRAM)
Dynamic RAM is the type of RAM that is widely used as the computer’s main memory storage location.
It is made up of an integrated circuit, which consists of a transistor and a capacitor. Transistors tend to leak in very small amounts.
This, in turn, causes the capacitor to discharge minute bits of information.
This is the primary reason why Dynamic RAM has to be refreshed from time to time.
Static RAM (SRAM)
Static RAM ideally consists of about four to six transistors.
It helps in retaining the data and information in the system as long as the power is supplied.
Static RAM offers a lot more convenience and speed as compared to dynamic RAM.
However, it is much more expensive as compared to now-prevalent dynamic RAM systems.
Therefore, although static RAM is more flexible in terms of usage options, dynamic RAMs are usually preferred for commercial reasons.
Types of Dynamic RAM
Synchronous Dynamic RAM (SDRAM)
As the name suggests, Synchronous Dynamic RAM helps in the synchronization of the memory speed along with the CPU Clock speed.
It prevents any latency time delay in the system, thereby supporting efficient functioning.
Thereby, the memory controller exactly knows the clock cycle speed.
The CPU can function with more information at the same time. It can transfer data at the rate of up to 133 MHz
Rambus Dynamic RAM (RDRAM)
The above name “Rambus” is derived from its company’s name. It was a very popular type of RAM in the early 2000s.
It possessed a transfer speed of up to 1 GHz. It was generally used for a variety of video game devices and other types of graphics cards.
Double Data Rate SDRAM (DDR SDRAM)
It is one of the types of memory data type that pertains to synchronicity. It can almost double the bandwidth when one considers a single data rate.
It uses a mechanism called “double pumping”, which can allow data transfer on both the rising as well as falling edges of the clock frequency signal.
DDR1 SDRAM is one of the youngest versions of the DDR SDRAM series. DDR2, DDR3, and most advanced DDR4 are recently developed.
Each of these mentioned generations delivers the data and information at higher transfer rates than the previous generation.
However, all of them work on more or else the same principles.
Final Thoughts
What type of RAM you may want to choose largely depends on the hardware you are currently using and many other technical factors of your computer system.
If you have an aging motherboard belonging to the 4th or 5th generation of Intel CPU, opting for DDR3 will be much easier and affordable concerning the compatibility issues.
However, if you own a recent motherboard available in the market like the 6th generation of Intel CPU, it is always advised to invest in DDR4 as it would be convenient for the long run.
In the case of professional design programs like Photoshop, the decrease in response time and latency can prove to be a major issue for working professionals.
At such times, DDR4 is one of the best options for providing visible improvement.
Making your computer system future-proof with DDR4 in a Skylake-based configuration can go a long way.
Considering all the factors mentioned above, you can make a good choice, taking into consideration your necessity and requirement.