What is GDDR6 Memory? (Explained)

What is GDDR6 Memory?

GDDR6 or Graphics Double Data Rate 6 refers to the 6th generation Synchronous Dynamic Random Access Memory or SDRAM developed by JEDEC or Joint Electron Device Engineering Council.

Technically, this successor of GDDR5 offers a higher bandwidth and uses a Quad Data Rate and Octal Data Rate in reference to the Write Command Clock and Command Clock respectively.


  • GDDR6 is the JEDEC developed memory that comes with high 16 GB/s per-pin bandwidth and a low operating voltage of about 1.3 volts maximum, to offer a higher performance with lower power requirement.
  • This particular video memory comes with a lot of useful features out of which the most significant is a split channel into two. This increases everything from the burst length to the access granularity and from data array prefetch to I/O width.
  • There are as many as 74 pins for the data and control signals in this memory module as opposed to 61 pins in its predecessor which further adds to its speed and performance level.
  • This specific video RAM is quite capable to support playing most modern games and have a wonderful experience and is also compatible with a DDR4 motherboard.

Understanding GDDR6 Memory

What is GDDR6 Memory

GDDR6 graphics memory is the latest inclusion which will help you a lot when you want your GPU to handle some of the hardest and most graphics intensive tasks.

This memory is built in your graphics card and therefore cannot be changed manually.

It is an upgrade from GDDR5 with a maximum bandwidth of 16 gigabytes per second in each pin which helps it to offer a much improved performance as compared to the earlier generations.

Depending on the model, this video memory can render graphics at a reasonably high speed of up to 24 GB/s which will bring a significant boost in the graphics performance while playing games.

The structure of this Video RAM is much similar to the earlier GDDR5X structure where the same 16n prefetch is retained.

However, the 32-bit data interface is split logically into two distinct channels, A and B, of 16 bits each.

These two channels in this memory are not dependent on one another in any way and therefore each of them offers a read or write memory access of 32 bytes or 256 bits wide.

The design and capability of this particular video memory makes it an actual game changer which offers 100% increase in power as compared to the earlier models.

It has a data transfer rate of about 16 GB/s per pin and the bandwidth is a stunning 64 gigabytes per second.

The power consumption is also quite low being 1.25 volts minimum as compared with other models but it may increase slightly when the performance needs are more demanding.

Apart from speed and improved performance, this graphics memory also offers incredible versatility and much better power efficiency.

With a low power requirement ranging between 1.2 and 1.3 volts, and even less in some specific models, you will get higher speed even when the voltage is down.

The innovative circuit design with Dynamic Voltage Switching feature in some pushes its power efficiency and bandwidth to the maximum to allow doing more demanding computing tasks at low power.

Available in larger quantities, lower latency and a high bandwidth, this graphics memory will allow you to dive into the details.

Since the channel in this video memory is split into two channels it is easier for the controller designers familiar with a GDDR5 device to work on a GDDR6 device because it will appear to them as two separate GDDR5 devices.

Each of these channels is of 16 bits and offers similar access granularity of 32 bytes as a single 32-bit.

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Their job is made even easier because there are some protocols in this memory which are similar to its predecessor in terms of write data mask and command set support.

This is offered with single as well as double mask granularity. It also has common interface training commands.

However, the 15 CA pins of the GDDR5 module are reduced into 12 CA pins in the GDDR6 memory module because it uses all these CA pins as Double Data Rate.

Moreover, since this memory module has two detached command interfaces for each of the two channels, at the component level the total number of control and data signals needed to be attached to the host system also increases.

There are as many as 74 pins in this graphics memory which can be broken down as follows:

  • 2 x 20 data
  • 2 x 12 CA
  • 2 CK and
  • 2 x 4 WCK.

On the other hand, its predecessor has only 61 pins according to the following configuration:

  • 40 data
  • 15 CA
  • 2 for CK and
  • 4 WCK.

One of the most significant benefits of the additional pins in the GDDR6 graphics memory is that in the pseudo channel mode it results in substantial savings in the number of signals needed to connect to the host.

Ideally, it requires only 66 of the total number of pins in the form and number of 2 x 20 data, 2 CK, 8 CA + 2 x 4 CA, and 2 x 4 WCK.

Features of GDDR6 Memory

One of the most significant and distinctive features of the GDDR6 graphics memory is that it comes with a data transfer rate of 16 GB/s. It also comes with a density of 16 GB and low voltage requirement of up to only 1.35 volts.

However, there are a few other specific and noteworthy features of this particular SGRAM such as:

  • This graphics memory offers two channels allowing the devices to be configured in two different channels or in pseudo-channel mode to operate
  • There are distinct command interfaces provided in each of these two channels with a common CK clock and a few specific pins such as RESET_n and VREFC so that both these channels operate at the same frequency
  • This BGA 180 video memory offers x 16/x 8 input-output width in it two channels
  • It offers access granularity of 32 bytes in the two channels even in pseudo 32B mode
  • The memory also offers Command/Address Bus Inversion or CABI as well as Data Bus Inversion or DBI
  • It also comes with data link protection feature at both full data rate and half data rate that offers exceptional error correction detection ability to it
  • It offers two supplementary mechanisms that help in giving REFRESH commands such as Per-bank REFRESH and Per-2-bank REFRESH that act as the most important tools to increase the sustained memory bandwidth and
  • The memory supports a boundary scan which is IEEE 1149.1 compliant for testing the interconnection on the PCB by using the ATPG or Automatic Test Pattern Generation tool.

One of the most critical circuits in the GDDR6 memory module is the data receiver.

This receiver of this SGRAM is designed to support very high speed inputs and therefore some allied functionalities have been incorporated in it in spite of the fact that the design of the actual receiver is Micron proprietary.

One important additional function of it is allowing the Data Receiver Reference Voltage or VREFD to be set separately for every data input in place of setting it on a per-byte basis as it is in the GDDR5 memory module.

This per-pin VREFD setting results in a variance in cross coupling of each of the lanes which, in turn, causes a slight difference in the vertical center of the data eye in each lane.

The defined step size in this case is 0.5% of VDDQ or 6.75 mV with the total range of it enlarged further.

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It also supports two separate termination strengths such as 60/40 ohms as it is in the GDDR5X memory module and 48/40 ohms.

Another notable inclusion in its function is the ISI or Inter System Interference on the channels.

This closes the data eye at the receiver. In addition to that, there is also a 1-tap DFE or Decision Feedback Equalization added which helps in opening the eye and detecting a symbol more reliably on the basis of the state of the earlier symbol being a 1 or a 0.

Both these features, DFE and VREFD, are programmed by the mode register bits where the DFE setting chooses different negative and positive VREFD levels for the two events.

Additional features of this graphics memory module include those to improve the input signaling speed and programming of output drivers.

For example, configuring the CK clock to terminate it on the PCB externally or internally through ODT at the power-up is one such useful feature.

The voltage for input reference for the CA pins may be produced internally or can be obtained externally from a resistor divider.

However, it allows offsetting the internal VREFC further through the mode register bits.

This is a new feature of this memory that enables tracking the differences in the VDDQ by the internal VREFC.

In addition to the above, WCK and data termination can also be done separately in this graphics memory since it comes with a 48 ohm alternative for the data put in.

This eventually allows better matching of the impedance to the channels.

As for the output, it is the driver equalization function that allows programming the output drivers in a much better way to match the characteristics of the system channel.

The internal clock rate is doubled inside this memory by the Quad Data Rate operation mode which is the same as the WCK clocking process of the GDDR5X memory.

This offers a much higher data rate without needing the 8 GHz WCK clock to be routed through the duty cycle of the lowest possible distortion between the DRAM and the host.

With all these design features and improved functionality of the GDDR6 graphics memory, it can focus on offering exceptionally high data rates with optimization of the memory controller, interface, and the DRAM and interconnect design.

GDDR6 vs GDDR5 – Differences

  • While the rate of data transfer in the case of the GDDR5 memory is only about 8 gigabytes per second that of the GDDR6 memory is nearly double than it ranging between 14 and 16 gigabytes per second
  • The GDDR6 video memory offers higher capacity per module in comparison to the GDDR5 memory since the VRAM is divided into two different modules
  • While the GDDR5 memory is available in five different sizes of 512 MB, 1 GB, 2 GB, 4 GB and 8 GB, GDDR6 memory in comparison only offers two different sizes of 8 GB and 16 GB
  • The power consumption by the GDDR6 memory is noticeably less as compared to that of the GDDR5 video memory being up to 1.35 volts as opposed to 1.5 volts of the latter
  • The access granularity offered by GDDR6 memory is double than the GDDR5 module mainly due to the presence of two channels that support 32 bytes of data each
  • The array prefetch of GDDR6 is 2 x 32 bytes through dual channels but that of the GDDR5 memory is only 32 bytes through the single channel
  • The 21 GB/s data transfer rate and other capabilities of the GDDR6 memory makes it a better performer than the GDDR5 memory in terms of gaming as well as in video editing
  • Burst length, CRC and density of the GDDR6 memory are double than those of the GDDR5 memory just as it is in the case of the I/O width and
  • The total signal count in the GDDR6 memory is higher being 40 DQ, DBI_n, EDC, 16 or 24 CA, and 12 CK, WCK adding up to 68 or 76 as opposed to 61 of GDDR5 being only 40, 15, and 6 of the three signal variants.
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GDDR6X vs GDDR6 – Differences

  • The GDDR6X video memory is superior to the standard GDDR6 memory in terms of speed and performance
  • The GDDR6X video memory uses Pulse Amplitude Modulation or PAM 4 encoding to generate different binary values with the help of the amplitude of the electrical signals instead of the NRZ or Non-Return to Zero encoding process followed in GDDR6
  • The bandwidth of the GDDR6X memory is double the bandwidth of GDDR6 because it can encode 2 bits per cycle instead on 1 by the GDDR6 memory due to the better encoding process
  • The power consumption for every bit transferred by the GDDR6X memory is about 15% less in comparison to the GDDR6 video memory
  • The overall power consumption of the GDDR6X is greater than GDDR6 memory because the former is quicker than the latter
  • Since the overall power consumption by the GDDR6X memory is more it runs significantly hotter than the GDDR6 memory
  • The GDDR6X memory is not a JEDEC standard but a Micron innovation which is not the case with the regular GDDR6 memory and
  • In terms of gaming and video editing, the performance of the GDDR6X memory is much better and higher than the regular GDDR6 memory.

Is GDDR6 Compatible with DDR4?

Yes, it is and will work fine, because DDR4 is a RAM and GDDR6 is a VRAM or Video RAM of the graphics card. These are two completely different things and the system memory has nothing to do with the video memory of the Graphics Processing Unit or GPU.

In fact, a DDR4 motherboard can support any type of modern graphics card whether it has a GDDR5, GDDR5X, GDDR6, GDDR6X and even HBM2 type of Video RAM.

However, it should have a PCIe or a Peripheral Component Interconnect Express slot, preferably running in the PCIe 3.0 x 16 modes which will help in getting the most out of the graphics card.

Is GDDR6 Good for Gaming?

Yes, GDDR6 is quite good for gaming because it has the ability to run almost any type of game at a moderately high resolution setting of 1080p.

However, you will not get a high visual and gaming experience if you play a game at a higher resolution or want the highest texture settings.

This is because higher texture and screen resolution will increase the requirement of Video RAM exponentially.

However, you will get quite a reasonable performance in terms of speed depending on the memory type.

For example, the new GDDR6 memory model of Samsung can hit a high speed of up to 24 GB/s which is much higher than the 18 GB/s speed of their earlier version.

This will result in an increase in the speed and performance by about 30%.

However, everything will depend on the game you play on your computer because every game is not created equal. Still, a GDDR6 memory will offer you a reasonably good gaming experience from the visual point of view for any type of game.


The generation of Video RAM is progressing in leaps and bounds to boost graphics performance and GDDR6 is no exception.

Through this article you have come to know a lot about this latest graphics memory and how it differs from others so much that it will be for you to decide whether or not it is good for you to use.

About Puja Chatterjee

Puja ChatterjeePuja Chatterjee is a technical writer with extensive knowledge about computers. She graduated from BIMS. Her expertise includes technology writing and client relationship management gained through over 12 years of experience. Follow Her at Linkedin.

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