AMD Embedded Processors and PCI Express Gen 4

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The latest AMD Embedded Processors have stolen a march on Intel Embedded Processors with regard to performance and connectivity.

AMD continue their rate of pace in the provision of capable solutions where their latest range of embedded processors (Ryzen & EPYC) are concerned – certainly concerning both performance and connectivity.

The AMD Embedded Ryzen range now supports PCI Express Gen 4 with 24 lanes. The 3500, 3600 & 3700X processors are in the embedded range and offer the availability of (at least) 5 years. The 3900X and 3950X are also in the embedded range but have a ‘standard’/consumer type availability – so around 2-3 years.

The AMD Embedded EPYC 7002 range also supports PCI Express Gen 4 with 128 lanes. The 7502P, 7262, 7302, 7352, 7452, 7502, 7552 & 7662 are in the embedded range and offer typical industrial availability of 5 years. Other models are also in the embedded range but have a 2-3 year availability. These processors are typically used to run enterprise applications, in virtualised and cloud computing environments, for software-defined infrastructure, high-performance computing, or data analytic applications.

With the availability of these AMD Embedded processors, PCIe Gen 4 bus technology has officially moved from behind the scenes to the front lines and AMD has turned PCIe Gen 4 bus technology into a reality.

PCIe Gen 4 is the next generation of high-speed interface and offers a data transfer rate that is twice that of PCIe Gen 3. The two standards are very similar in structure – their coding method remains the same but the frequency has doubled.

  • PCIe Gen 3 offers a data transfer rate of 8 Giga Transfers per second, which is the rate of bits transferred per second that gets transmitted from the host to the end device or endpoint.
  • PCIe Gen 4 doubled from 8 Giga Transfers to 16 Giga Transfers per second. The x16 bandwidth reaches 31.5 Gigabytes per second, and the two-way approach 64 Gigabytes per second. This means that PCIe Gen 4 has a channel speed that is even higher than the average processor or memory bandwidth.

The common NVMe SSDs in the industry use 4 PCIe lanes, so the theoretical rate of PCIe Gen 3 is 4 Lanes x 8 = 32 Giga transfer per second, while PCIe Gen 4 are Giga Transfer per second per lane speed so 4 Lanes x 16 = 64 Giga Transfers per second.


The increase in bandwidth allows faster data transfer from PCIe to endpoints such as SSD or GPU.

In the past, it was said that the hard disk was the biggest bottleneck of the PC. Indeed, in the era of HDD or SATA SSD, the AHCI protocol is supported and the very slow SATA channel with a speed of only 600 Megabytes per second leads to hard disk read and write speeds that lag behind the processor and memory. When the three are working together the hard disk often lags making the whole machine inefficient.

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However, now M.2 NVMe SSD’s can use the PCIe Gen 4 channel and increase the read and write speed to about 4000-5000 megabyte per second, which is nearly 10 times higher than the previously measured read and write speed of SATA SSD – and about 30-40% higher than PCIe Gen 3 SSD. The speed of the hard drive is really, finally catching up.

Like PCIe Gen 3, PCIe Gen 4 is forward and backward compatible. This means that PCIe Gen 4 can directly replace PCIe Gen 3 but it also means that if a PCIe Gen 3 card is connected to the PCIe Gen 4 slot the card will comply with the PCIe Gen 3 specification and only need to use 8 PCIe Gen 4 lanes. In other words, in addition to the higher bandwidth outlined above, PCIe Gen 4 also allows designers and system integrators to increase the number of expansion cards on the platform.

Higher data transfer rate and lower latency.

A GPU card connected to the PCIe Gen 4 slot can transfer the data being loaded in the GPU memory faster and, therefore, reduce the delay on the PCIe bus. As the file size and graphics complexity of video games continue to increase – and machine learning applications continue to require larger and larger data sets, so PCIe Gen 4 will play an important role in increasing the frame rate and reducing the computing time.

Similar to a PCIe Gen 4 GPU, connecting a PCIe Gen 4 NVMe SSD will result in a higher data transfer rate and lower latency. It is still forward or backward compatible, so you can connect any SSD Gen to the PCIe Gen 4 interface and the speed will depend on the controller generation of the PCIe SSD.

With the advent of the new AMD Ryzen and EPYC 7002 processors, PCIe Gen 4 has caused a lot of discussion. Note, however, that the Intel ICE LAKE-SP/TIGER LAKE-UP3/ and 11th generation Rocket Lake will also support PCIe Gen 4.

With the demand for future platforms, SSD manufacturers have launched PCIe Gen 4 NVMe SSDs one after another which will surely become a trend.

On the contrary, the effectiveness of PCIe Gen 4 at the current stage in the graphics card arena has only been increased by 2%. Whether there is a need to upgrade will be a matter of opinion.



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