▷ Types of ram and encapsulated memory that currently exist

Computer memories are plentiful and we must know the types of RAM that are on the market and the available packages. RAM is a necessary component to run our equipment, and its performance depends largely on it. That is why we will see and explain all these types of memories, their characteristics, as well as the different packages or formats that we can find.

Index of contents

As we can suppose, there are many types of memories and also formats, since there is not the same space on a laptop as on a desktop PC. There are also the memories of mobile devices such as Smartphone and Tablet that will also have their own, and we will also see them.

What is RAM

RAM or random access memory is a physical component of our computer that is available in modular form for installation on the computer's motherboard. In some cases it will be inserted in a fixed way in the equipment, as in mobile cases.

The RAM memory is in charge of loading all the instructions that are executed in the processor so that it can access them. These instructions come from the operating system, our interaction with the computer, and input / output devices. Inside the RAM memory all the programs that are running at the moment are stored in order to be able to send their instructions much faster than if they did it from the hard disk.

It is called random access memory because it is possible to read and write to any of its memory locations without having to respect a sequential order for access. It is also volatile, which means that when we turn off the computer all its content will disappear and it will be empty.

Construction of RAM memory: types of encapsulations for PC

Before looking at the different technologies and types of RAM, let us know the types of packages that we have available for them. These terms appear in the list of types of RAM memories, so it is good to know them beforehand and to know the differences of each one of them.

The packages consist of a PCB where the memory chips or modules are installed. In addition, it has the necessary connection to install it on the motherboard and make the communication with the processor effective.

RIMM: these modules mounted RDRAM or Rambus DRAM memories that we will see later. These modules have 184 connection pins and a 16-bit bus. SIMM: This format was used by older computers. We will have 30 and 60 contact modules and 16 and 32 bit data bus. DIMM: this is the format currently used for DDR memories in versions 1, 2, 3 and 4. The data bus is 64 bits and can have: 168 pins for SDR RAM, 184 for DDR, 240 for DDR2 and DDR3 and 288 for DDR4. SO-DIMM: it will be the specific DIMM format for portable computers. It is smaller and more compact than the previous ones and will have a number of connection pins of 144 for SDR RAM, (32 bits), 200 for DDR and DDR2 RAM, 204 for DDR3 RAM and 260 for DDR4 RAM. Mini DIMMs: they have the same number of pins as SO-DIMMs, but they are even smaller, we are talking about 82 mm long by 18 mm high. They are oriented to the installation in NUC or Mini PC. FB-DIMM: DIMM format for servers.

SRAM memories

They are also random access memories, although in this case they are static. These types of memories are faster and more reliable than DRAM memories because they need to be refreshed less times than DRAM memories to maintain their content.

The construction of these RAM memories is based on a flip-flop circuit to allow the current to flow from one side to the other depending on which transistor is activated of the two that make up the circuit. In this way, the data can be stored in this circuit without needing to be constantly refreshed. These memories require more energy, but they are faster, but also more expensive to manufacture. They are normally used to build the processor cache memory.

DRAM memories

The name means Dinamic RAM. These would be the first memories based on silicon semiconductors, and were originally asynchronous. The most important feature introduced by these memories was their transistor and capacitor structure. It was possible to store a data inside a memory cell feeding the capacitor of it hundreds of times per second so that this data remained stored.

This type of memory is volatile, so it will lose its content when it is turned off. DRAMs were of the asynchronous type, so there was no element that synchronized the frequency of the processor with the frequency of the memory itself. Consequently, there was less communication efficiency between the two elements. But some time later, SDRAM memories (synchronous RAM memories) appeared, which implemented a clock in charge of synchronizing them with the processor.

This memory is the one used to build the RAM memories of our computer. They are cheaper and easier to build than SRAMs, but also slower. There are the following types of DRAM memories:

FPM-RAM (Fast Page Mode RAM): These memories were used for the first Intel Pentium. Its design consisted of being able to send a single address and in exchange receive several of these consecutive ones. This allows for better response and efficiency as you do not need to be continuously sending and receiving individual addresses.

EDO-RAM (Extended Data Output RAM): it is the improvement of the previous design. In addition to being able to receive contiguous addresses simultaneously, the previous column of addresses is being read, so there is no need to wait for addresses when one is sent.

BEDO-RAM (Burst Extended Data RAM): improvement of the EDO-RAM, this memory was able to access various memory locations to send data bursts (Burt) in each clock cycle to the processor. This memory was never commercialized.

Rambus DRAM: were the evolution of asynchronous DRAM memories. These improved both the bandwidth and its frequency, reaching up to 1200 MHz and a 64-bit bus width. They used a RIMM package and are currently deprecated.

SDRAM (Synchronous type memory): The big difference with previous versions of DRAM is that it has an internal clock that is capable of synchronizing the frequency of the memory with the processor to improve access times and communication efficiency.. This is the type of RAM that is used today, and there are several versions of it that we will now see.

SDR RAM: These were the predecessors of the well-known DDR RAM and are synchronous. They were built under a DIMM encapsulation of 168 contacts and until about 10 years ago they were the ones that our computers had, since they were used in AMD Athlon and Pentium 2 and 3. They only supported a size per module of 512 MB.

DDR SDRAM Memory (Current)

Because they are current RAM memories, we have decided to put them in a separate section, since there are quite a few variants within this family of RAM memories. All of them are synchronous type, and have been used during these years back until today.

DDR memories allow the transfer of information through two different channels simultaneously in the same clock cycle (Double Data), something that allows us to achieve higher performance and access speeds. Of course there are several versions of these RAM memories used in today's computers.

DDR SDRAM (first version)

This is the first version of DDR RAM that we currently know of. They are mounted on 182 -pin DIMMs and 200-pin SO-DIMMs. These memories operate at 2.5 Volts and have a clock speed between 100 MHz and 200 MHz.

DDR RAMs were the first to implement Dual Channel technology, which allows RAM memory modules to be divided into two banks or slots to exchange data with the bus on two simultaneous channels. For example, if the modules are 64 bits, we will have an exchange bus width of 128 bits. The following RAM memory configurations have existed regarding speed:

Standard name	Clock frequency	Bus frequency	Transfer speed	Module name	Transfer capacity
DDR-200	100 MHz	100 MHz	200 MHz	PC-1600	1.6 GB / s
DDR-266	133 MHz	133 MHz	266 MHz	PC-2100	2.1 GB / s
DDR-333	166 MHz	166 MHz	333 MHz	PC-2700	2.7 GB / s
DDR-400	200 MHz	200 MHz	400 MHz	PC-3200	3.2 GB / s

DDR2 SDRAM (second version)

They are the second version of DDR memory, and have the novelty compared to the previous ones in that they are capable of doubling the transferred bits to 4 instead of 2 for each clock cycle.

The encapsulation used is also of the DIMM type, but with 240 contacts and the wrist in a different place to differentiate them from the previous ones. These modules work at 1.8 V, so they consume less than DDR. There are also variants with So-DIMM and Mini DIMM encapsulation for laptops and DDR2L versions for laptops with 1.5 V consumptions. A DDR2 memory cannot be installed in a DDR slot or vice versa, as they are not compatible with each other.

The configurations that have existed are the following:

Standard name	Clock frequency	Bus frequency	Transfer speed	Module name	Transfer capacity
DDR2-333	100 MHz	166 MHz	333 MHz	PC2-2600	2.6 GB / s
DDR2-400	100 MHz	200 MHz	400 MHz	PC2-3200	3.2 GB / s
DDR2-533	133 MHz	266 MHz	533 MHz	PC2-4200	4.2 GB / s
DDR2-600	150 MHz	300 MHz	600 MHz	PC2-4800	4.8 GB / s
DDR2-667	166 MHz	333 MHz	667 MHz	PC2-5300	5.3 GB / s
DDR2-800	200 MHz	400 MHz	800 MHz	PC2-6400	6.4 GB / s
DDR2-1000	250 MHz	500 MHz	1000 MHz	PC2-8000	8 GB / s
DDR2-1066	266 MHz	533 MHz	1066 MHz	PC2-8500	8.5 GB / s
DDR2-1150	286 MHz	575 MHz	1150 MHz	PC2-9200	9.2 GB / s
DDR2-1200	300 MHz	600 MHz	1200 MHz	PC2-9600	9.6 GB / s

DDR3 SDRAM (third version)

In this case, energy efficiency is improved, by working at a voltage of 1.5 V in the desktop version. The encapsulation is still a 240-pin DIMM type and the capacity per memory module is up to 16 GB. They are also not compatible with the rest of the specifications.

A negative aspect of the subsequent versions of the DDR is that, although the speed increases, so does the latency in them, although in essence, they are faster as long as the previous generation.

In this new version of RAM, a few variants were introduced depending on the needs of portable computers and the invention of Mini PCs (NUC), which are basically desktop computers, but with very small dimensions and very low consumption.

DDR3: they are the traditional desktop computers in DIMM encapsulation and working at 1.5 V. DDR3L: in this case they work at 1.35 V and are aimed at laptops, NUCs and servers under So-DIMM, SP-DIMM and Mini DIMM. DDR3U: they go down to 1.25 V and are not overly used. LPDDR3: this memory consumes only 1.2 V and are intended for use on Tablet and Smartphone. Also, they consume very little voltage when not in use, making them very efficient. These types of chips are directly soldered to the PCB of the device.

Let's see now the configurations that we have in the market:

Standard name	Clock frequency	Bus frequency	Transfer speed	Module name	Transfer capacity
DDR3-800	100 MHz	400 MHz	800 MHz	PC3-6400	6.4 GB / s
DDR3-1066	133 MHz	533 MHz	1066 MHz	PC3-8500	8.5 GB / s
DDR3-1200	150 MHz	600 MHz	1200 MHz	PC3-9600	9.6 GB / s
DDR3-1333	166 MHz	666 MHz	1333 MHz	PC3-10600	10.6 GB / s
DDR3-1375	170 MHz	688 MHz	1375 MHz	PC3-11000	11 GB / s
DDR3-1466	183 MHz	733 MHz	1466 MHz	PC3-11700	11.7 GB / s
DDR3-1600	200 MHz	800 MHz	1600 MHz	PC3-12800	12.8 GB / s
DDR3-1866	233 MHz	933 MHz	1866 MHz	PC3-14900	14.9 GB / s
DDR3-2000	250 MHz	1000 MHz	2000 MHz	PC3-16000	16 GB / s
DDR3-2133	266 MHz	1066 MHz	2133 MHz	PC3-17000	17 GB / s
DDR3-2200	350 MHz	1100 MHz	2200 MHz	PC3-18000	18 GB / s

DDR4 SDRAM (fourth and current version)

These memories operate at a higher frequency and are mounted on a 288-pin DIMM package. Despite the fact that the frequency increases considerably, these memories are even more efficient, since they work at 1.35 V in desktop PCs and 1.05 in the cases of laptops. The most powerful versions up to 4600 MHz work at 1.45 V.

Another novelty that DDR4 implements is that they are capable of operating in triple and quadruple channels (Triple Channel and Quad Channel). In addition, we already have the possibility of mounting a module of up to 16 and 32 GB in a single package.

Likewise, these memories are divided into 4 different types depending on their use:

DDR4: These are those used in desktop computers, they come in a DIMM with 288 contacts and operate at voltages between 1.35 and 1.2 V. DDR4L: These memories are designed for laptops and servers and are mounted on a 1.2 V So-DIMM module. DDR4U: As with the previous ones, they are mainly used for servers and also operate at 1.2 V. Their use is scarce and DDR4L are more widespread. LPDDR4: They are designed for mobile devices and work at 1.1 or 1.05 V, although they are less fast than desktop DDR4 as normal. They work at about 1600 MHz, although there is also another version called LPDDR4E that reaches 2133 MHz.

We will see its corresponding tablet:

Standard name	Clock frequency	Bus frequency	Transfer speed	Module name	Transfer capacity
DDR4-1600	200 MHz	800 MHz	1600 MHz	PC4-12800	12.8 GB / s
DDR4-1866	233 MHz	933 MHz	1866 MHz	PC4-14900	14.9 GB / s
DDR4-2133	266 MHz	1066 MHz	2133 MHz	PC4-17000	17 GB / s
DDR4-2400	300 MHz	1200 MHz	2400 MHz	PC4-19200	19.9 GB / s
DDR4-2666	333 MHz	1333 MHz	2666 MHz	PC4-21300	21.3 GB / s
DDR4-2933	366 MHz	1466 MHz	2933 MHz	PC4-32466	23.4 GB / s
DDR4-3200	400 MHz	1600 MHz	3200 MHz	PC4-25600	25.6 GB / s
…	…	..	…	…	…
DDR4-4600	533 MHz	2133 MHz	4600 MHz	PC4-36800	36.8 GB / s

GDDR memories

In addition to the traditional DDR RAM, there is also the variant GDDR (Graphics Double Data Rate), which refers to the memories that are designed for graphics cards.

These memories also work under the DDR standard specified by JEDEC, sending two bits or 4 for each clock cycle, although in these cases they are optimized to reach higher frequencies and greater bus width to shorten the access times to the instructions stored in its interior.

Of course the price of them also has a lot of influence, since they are much more expensive to manufacture than normal DDRs. Like DDR, there are different evolutions that have increased the performance of our graphics cards considerably.

GDDR: They were the first to hit the market and are based on DDR2 memory. The effective frequency of these was between 166 and 950 MHz with latency of 4 to 6 ns. These memories were mounted on older ATI Radeon 9000 series cards and Nvidia GeForce FX. GDDR2: It is also based on DDR2 memory and basically they were an optimization of the previous ones to reach a frequency between 533 and 1000 MHz and a bandwidth of between 8.5 to 16 GB / s. They were mounted on the A MD HD 5000 and the Nvidia GT 700, among others. GDDR3: These memories were designed by ATI for its Radeon X800 cards, although the first to use it was the Nvidia GeForce FX 5700. In addition, they were used to build the PlayStation 3 and Xbox 360 consoles. These memories operate between 166 and 800 MHz. GDDR4: These memories were based on DDR3 technology, although their existence was quite short and they were quickly replaced by GDDR5. This memory was used by some AMD graphics cards like AMD HD3870 and the like that faced the Nvidia 8800 GT with GDDR3. GDDR5: these we have seen quite a bit in recent years, being used until today by cards like the Nvidia GTX 1000 and a host of AMD cards, such as the Radeon HD, R5, R7, R9 and even the Newest RX Polaris. The bus widths of these memories are between 20 GB / s on a 32-bit bus and 160 GB / s on a 256-bit bus, and the effective memory frequency reaches up to 8 Gbps. They are also mounted on the latest consoles, such as the PS4 and the Xbox One X. GDDR5X: It is an extreme evolution of the GDDR5 used by Nvidia for its 1080, 1080 Ti and Titan X cards, capable of reaching up to an effective frequency of 11 Gbps and a bandwidth of no less than 484 GB / s on a 352 bit bus. GDDR6: We have reached the current era of Nvidia graphics cards, which are exclusively mounted on the brand's new RTX Turing range. These memories have a high cost and are capable of reaching a frequency of 14 Gbps with a bandwidth of 672 GB / s on a 384 bit bus, used by the Nvidia Titan RTX, the most powerful desktop card ever created until the date.

Well, this is all about the types of RAM that have been used in recent times, as well as its main characteristics. The idea is to update this article with the new technologies that are implemented.

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We hope you found this article interesting. If information is missing, write us in the comments, we will be aware. What RAM memory does your computer and graphics card have?