Pcie 2 x1 speed: PCI Express Interface

PCI Express Interface

PCI Express 3.0 Technical Challenges

UPDATE: For information PCIe 4.0 and PCIe 3.0 slots and speeds, read our latest blog that discusses both. For more information on PCIe 4.0, specifically, check out Everything You Need to Know About PCIe 4.0.

Correctly routing PCIe 3.0 signal traces is a design challenge that few companies can handle well, and taking shortcuts in system host board, single board computer, and backplane designs which utilize the PCI Express 3.0 interface will always result in suboptimal system performance. 

With new technologies such as blockchain driving demand for flawless communication between components, this simply is no longer an option. Just look at the new blockchain supercomputer in the making and you’ll understand just how important PCIe slots are in today’s market.

Another great article to read is Blockchain Explained: Part 2 where we cover the technology roadblocks and how high-performance computing manufacturers are trying to cram as many GPUs into a system that can utilize all the PCIe slots it can handle.

For example, with all previous generations of PCI Express it was best practice to keep traces well below 16 inches to insure optimum performance, but the PCIe Gen3 specification makes the length requirement even more restrictive, which is why it’s so important to understand the difference between PCI Express 3.0, 2.0 and 1.1.

Rugged computers from Trenton Systems are:

  • Engineered to standup up to the rigors of industrial and military computing applications
  • Designed to support for both industry standard and custom PCI Express plug-in cards
  • Built to maximize system deployment flexibility
  • Built to last with 7-10 year long-life processor and backplane components all backed by our 5-year product warranty
  • Manufactured in our ISO facilities located in the United States

The Gen3 specification requires a pre-validation of the link before any data transmission, and if the automatic equalization training cannot establish a reliable link, then it won’t allow the transmission of data at 8Gt/s speeds, resulting in slower than expected card-to-card as well as card-to-SBC data transfers within a typical system design.

These considerations are critical in the design of a backplane, such as the HDB8259, which supports multiple Gen3 high-performance I/O cards inside a single integrated system.

PCIe 3.0, PCIe 2.0, PCIe 1.1 Differences

With silicon for PCI Express® 3.0 released by various chip vendors, it might be a good idea to review the interface differences between PCIe 3.0, PCI Express 2.0 and PCI Express 1.1. Understanding these interface differences will allow for successful use of the latest PCI Express interface technology into embedded applications.

Does it matter that the single board computer / system host board and option card interface is PCI Express version 1.1, 2.0 or even the new PCIe 3.0? Not really, because the basic SBC to option card interconnect functionality is not affected by PCIe version. The reason for this is that the PCI-SIG (Peripheral Component Interconnect Special Interest Group) was forward  thinking when PCI Express 1.1 was first developed.

The PCI-SIG built the basic PCIe interconnects in such a manner as to ensure both scalability and backwards compatibility between the differing PCIe interfaces. This critical specification feature enables the computer’s SBC/SHB, embedded motherboard or backplane hardware to operate with just about any PCI Express option card regardless of interface version.

The potential for increased data throughput and performance within any computing platform is the primary difference between the PCI Express 3.0, 2.0 and 1.1 interfaces. A PCI Express 2.0 board installed in an industrial computer will send its data to the system host board twice as fast as older PCI Express 1.1 boards.

The same scenario plays out in an embedded motherboard. If the motherboard is equipped with PCIe 2.0 card slots, then any PCIe 2.0 card placed into one of these slots will send its data to the board’s CPUs twice as fast as in a PCIe 1.1 system. This speed advantage is cumulative and can be critical in high-performance computing applications.

Summary of PCI Express Interface Parameters:

  • Base Clock Speed: PCIe 3.0 = 8.0GHz, PCIe 2. 0 = 5.0GHz, PCIe 1.1 = 2.5GHz
  • Data Rate: PCIe 3.0 = 1000MB/s, PCIe 2.0 = 500MB/s, PCIe 1.1 = 250MB/s
  • Total Bandwidth: (x16 link): PCIe 3.0 = 32GB/s, PCIe 2.0 = 16GB/s, PCIe 1.1 = 8GB/s
  • Data Transfer Rate: PCIe 3.0 = 8.0GT/s, PCIe 2.0= 5.0GT/s, PCIe 1.1 = 2.5GT/s

PCIe 3.0 features a number of interface architecture improvements, but communicates at the same interface speeds used in PCIe 2.0. PCIe 3.0 achieves twice the communication speeds of PCIe 2.0 through various architecture and protocol management improvements.

Trenton single board computers, such as the BXT7059 and TSB7053, support a wide variety of PCI Express option card interfaces. Embedded motherboards, such as the JXM7031 and WTM7026, feature multiple PCI Express option card slots and the BPG8032 and BPG7087 backplanes are examples of PICMG 1.3 backplanes with built-in PCI Express 2.0 computing hardware support, while the BPX8093 PCIe backplane supports PCI Express 3. 0.

Trenton BPG8032 PCI Express Backplane

The BPG8032 PCI Express backplane is ideal for video wall controllers, graphics processing and GPU computing system solutions. This backplane supports one single board computer & seventeen x16 PCI Express I/O option card slots. Each option card slot uses a x16 mechanical connector to maximize system design flexibility.  The BPG8032 can take full advantage of PCI Express 2.0’s data throughput capacity when used with Trenton Systems single board computers.

At Trenton, our engineers are recognized for their knowledgeable and innovative approach to crafting industrial computing solutions, including the design, prototyping and manufacturing of embedded system components for mission critical applications. For a quotation or inquiry on products supporting PCI Express, Contact Trenton or call 770-287-3100 or 800-875-6031.

What are the top uses of PCIe x1 Slots?-C&T Solution Inc.


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News&Events Blog What are the top uses of PCIe x1 Slots?

 

PCI Express slots are one of the essential technologies that exist on a motherboard. PCIe slots are utilized by various performance accelerators and peripheral cards due to their high power and connection speed, allowing data-intensive processors like GPU cards to connect smoothly with the CPU. There are various sizes of PCIe slots from x1 to x16, and often we come across questions on what are the top uses of PCIe x1 slots. Therefore, in this blog, we will discuss PCIe expansion slots and the top use case for PCIe x1 slots .

 

What Are the Different Types of PCIe Slots?

PCIe or Peripheral Component Interconnect Express is the standard that was developed to provide motherboards with high-speed serial expansion slots for data-intensive devices to the CPU. Compared to the older PCI standard, PCIe has various improvements from higher maximum throughput, fewer I/ O pins, and a smaller form factor. PCIe slots have multiple sizes, including PCIe x16 slots, PCIe x8 slots, PCIe x4 slots, and the smallest PCIe x1 slots. When getting peripheral cards, you want to make sure to get the same size as the PCIe slots. Fortunately, if you have smaller PCIe cards, they can fit into bigger PCIe slots. For example, a PCIe x1 WiFi card can fit into PCIe x4 slots without a problem. However, you want to optimize your PCIe lanes inside the slots by fitting PCI x1 cards to PCIe x1 slots without wasting three or more PCIe lanes.

 

What are PCIe Lanes?

When deciding on the combination of expansion cards for your motherboard, you want to understand what PCIe lanes are. PCIe lanes or PCIe data lanes are the conductor pins inside the PCIe slots. Typically, the size of the PCIe slots also represents the number of PCIe lanes. For instance, PCIe x16 slots have x16 PCIe lanes, and PCIe x1 slots have x1 PCIe lanes. Standard motherboards usually have around 20 to 24 PCIe lanes distributed among different PCIe slots built on them. However, some PCIe slots also have more data lanes than their size. Therefore, some PCIe x16 slots might only have x8 PCIe lanes. Usually, this wouldn’t be problematic, even if you want to attach a GPU card to it. Newer PCIe generations have a higher bandwidth speed per lane compared to their predecessors. Therefore,PCIe x1 slots have enough bandwidth speed for various peripherals cards such as port expansion cards, network cards, and sound cards.
 

PCIe Generations and Speed

Source: Premioinc.com

There have been six generations of PCI Express, from PCIe Gen 1 to PCIe Gen 6. The PCI Express interface doubles its connection speed for every new generation. The current most popular PCIe slots are the PCIe Gen 3 with 1 Gbps of speed per lane. For example, PCIe Gen 3 x1 slots have a bandwidth speed of 1 Gbps, and PCIe Gen 3 x16 has 16 Gbps of connection speed. However, current processors, computers, and motherboards are starting to adopt PCIe Gen 4 architecture with newer applications requiring PCIe Gen 4 performance speeds.

The latest PCIe architecture innovation is much faster than current processors sold on the market, which creates a delay in the commercialization of hardware products with faster PCIe generation speeds. This technology adoption model and its progression for mass deployment are normal because of the real-world application demands. PCIe gen 4 hardware products are becoming more prevalent at the time of this blog article, especially in high-performance computing in data centers. Compared to 3rd Gen PCIe x1 slots with 1 Gbps, now 4th Gen PCIe x1 slots have 2 Gbps of connection speed.

 

What is PCIe x1 Slot?

PCIe x1 slots have only one PCIe lane. Despite having only one PCIe lane, PCIe x1 slots are useful for various lower-power PCIe peripheral cards. PCIe x1 slots are the smallest PCI Express slots with the lowest throughput compared to bigger PCIe slots like the PCIe x16 slots. However, PCIe x1 cards can fit into all PCIe expansion slots, including x4, x8, and x16 PCIe slots. Often it is underestimated what they can do with the PCIe x1 slots. Therefore, we will show you what peripheral expansion cards you can attach to a PCIe x1 slot.
 

What are the top uses of PCIe x1 Slots?

Despite PCIe x1 slots having one PCIe lane, they are still useful, and in some cases, you want to use the PCIe x1 slots instead of bigger slots like the PCIe x16 to stay optimized. Here are some of the expansion cards you can fit into PCIe x1 slots.

  • Modems and Network Cards (Wired and Wireless)
  • Sound card
  • SATA expansion card
  • USB port expansion
  • TV Tuner Cards
  • Video Capture Cards
  • PCIe Riser Cards

1. Modems and Network Cards

Adding either wired or wireless expansion cards to the motherboard can be accomplished with PCIe x1 slots. You can attach a PCIe x1 WiFi card or 1G PCIe Ethernet card to your PCIe x1 slot. Motherboards often already have an ethernet built in. However, a PCIe x1 Wi-Fi card is one of the ways to add Wi-Fi connectivity to your computer. PCIe x1 slot can support all types of wireless cards, including the latest Wi-Fi 6 protocol. However, a PCIe x1 slot can only support 1 Gigabit Ethernet network or RJ45 Ethernet LAN (Local Area Network) cards; for 10GbE expansion, you will require a PCIe x4 slot.

 

2. Sound Cards

Commonly sound cards are not necessary since most motherboards have a built-in audio chipset. However, some audiophiles or people who take audio quality more seriously can install a sound card to the PCIe x1 slot to get a higher audio quality with more accurate sound. With a sound card installed in your PCIe x1 slot, your computer can have a better-quality sound, more ports, and better shielding against electromagnetic interference.

3. SATA Expansion Cards

You can get a PCIe x1 SATA expansion card to add more SATA ports when you want to add more SATA hard drives to your computer. The 3rd Gen PCIe x1 slots have 1Gbps of data transfer speed and can handle multiple SATA expansion with SATA SSD (Solid State Drives) or SATA HDD storage. Since SATA SSDs have around 550 Mbps and SATA HDDs have around 150 Mbps of data transfer speed, PCIe x1 SATA card would not have a problem handling multiple SATA storage drives great for NAS (Network Attached Storage) systems .

Learn More About SSD vs HDD Storage Drives

4. USB Port Expansion Cards

PCIe x1 can also support USB port expansion. Therefore, if you need more USB ports on your computer, you can use the USB PCIe x1 cards to add more USB 3.0 type A or even USB type C ports to your computer. Other I/Os can also be added through PCIe x1 slots, by simply finding the I/O expansion card with the PCIe x1 form factor.

Learn More About Different Types Of USB Generations

5. TV Tuner Cards

Another use of PCIe x1 slots is a TV tuner card. With a PCIe x1 TV card, you can let your device receive television signals directly on your computer, transforming your computer into a television. Some cards even allow your computer to record the live TV shows right off the cable to watch them later.

6. Video Capture Cards

 

Video capture cards enable your computer to receive any video source from a camera or other external devices like the gaming console, TV, or DVD player and convert these video signals into digital data that can be stored on your computer. These converted data can be streamed live or saved for post-editing. Typically, FHD video capturing uses a PCIe x1 expansion card, while more high definition 4K capture cards require at least PCIe x4 expansion slot to handle the bandwidth requirement.

7. PCIe Rise Cards

If you need more PCIe slots on your motherboard, you can utilize PCIe riser cards, also known as splitters. It is important to note that PCIe riser cards only increase the number of slots, and the bandwidth of the PCIe will stay the same, distributed evenly among the PCIe slots on the riser cards. Therefore, a riser card with four PCIe x1 slots attached to a PCIe x1 slot will have a quarter of the PCIe x1 bandwidth on each slot.

What’s Next? PCIe, mPCIe, M.2

 

The current PCIe Gen 3 slots have started to be replaced with PCIe Gen 4, resulting in double the transfer and bandwidth speed, which means you can install more powerful hardware on a smaller PCIe slot. Furthermore, other expansion slots run under a PCI Express interface with smaller form factors, such as mPCIe and M. 2 slots. There is one PCIe lane on a mPCIe slot, while there are two to four PCIe lanes on M.2 slots, which makes the M.2 expansion slot the future of small and powerful expansion slots.

Learn More About M.2 Expansion Slots
 

PCI e x1 — what is it?

Hello everyone! Today we will discuss the PCI E x1 bus: what kind of connector it is, what it is for, what speed it has, how many slots of this type can be on a computer, and whether x1 devices can be inserted into PCI Express x16. What is PCI Express? nine0003

The main drawback is that the throughput is too low for growing data sets.

Using the software model of the PCI protocol, the developers have created a more advanced interface. If in the interface of the old format data was transferred one by one, waiting in the common stack, then in PCI-E it became possible to transfer them simultaneously.

In fact, peripheral devices are a network with a star topology. Each of the connected devices can directly access the other, without involving the CPU and RAM in the process. nine0003

The effect of the number of lines on the data transfer rate

Having undergone a number of changes, this interface is now available in the 5th generation. It is characteristic that different versions of the interface use the same type of physical connections, which are usually made in 4 main sizes: x1, x4, x8 and x16.

They differ in length. This affects the number of connectors that connect to the motherboard at the same time. They are also called lines. One line is a track of a signal pair: contacts for sending and receiving data. nine0003

The throughput depends on the number of connectors. That is, the more of them, the faster a particular port will work. In the 4th generation, the throughput per line x1 was 1.969 GB / s. In the 5th generation, developed in 2019, it increased to 3.938 GB / s. In version 2.0, the speed was even lower — 500 MB / s. Today, this version is almost never used. In 3.0, the throughput was raised to 984.6 MB / s. Such a port can still be found on motherboards released after 2010. nine0003

What can be connected via the PCI-E x1 interface

Today, Wi-Fi and WiMax adapters, GSM and GPS modules, solid state drives, controllers for USB and COM ports, indicator LEDs, adapters for GSM SIM cards and WCDMA. The port has reserved pins for future devices.

The number of PCI-Express slots depends on the motherboard model, but there is always at least one. On average, there are 3-4 such slots. nine0003

Theoretically, it is possible to install x1 device in x16 port. In practice, it all depends on each specific device: how exactly the power is supplied and whether the device is activated. The worst thing that can happen is that it simply won’t work. It is impossible to break anything. Read more about what PCI-E x16 is here.

And one more thing. Typically, most motherboards only have one x16 port. More only on advanced gaming modifications. It is possible that the slot will already be occupied by a video card, so you won’t connect anything anymore — unless, of course, you want to be content with the graphics core integrated into the processor. nine0003

I also advise you to read «What is the difference between PCI and PCI E» and «All connectors on the motherboard.» I would be grateful if you share this post on social networks. Till tomorrow!

Sincerely, the author of the blog Andrey Andreev.

Actual Bandwidth: PCI Express and Thunderbolt

Everything you need to know about the current PCI Express and Thunderbolt bandwidth capabilities and limitations when building your next PC. nine0003

We are in the future!

It’s time to continue our scintillating look at interfaces and bandwidth limits. We turned our attention to PCI Express and Thunderbolt.

First, PCI Express: what exactly does it mean when you have a PCIe 2.0 x8 connection? And does it matter if your connection is x8 or x16?

PCI Express

The PCI Express interface is a bit confusing. A PCIe connection consists of one or more data lanes connected in series. Each lane consists of two pairs of conductors, one for receiving and one for transmitting. You can have one, four, eight, or sixteen lanes in a single consumer PCIe slot — labeled x1, x4, x8, or x16. Each lane is an independent connection between the PCI controller and the expansion card, and the linear bandwidth is linear, so an eight-lane connection will have twice the bandwidth of a four-lane connection. This helps to avoid bottlenecks between, say, the processor and the graphics card. If you need more bandwidth, just use more lanes. nine0003

There are several different physical connections, each of which can function electrically as a slot with fewer lanes and can also hold a physically smaller card. A physical PCIe x16 slot can host an x1, x4, x8, or x16 card and run an x16 card at x16, x8, x4, or x1. PCIe x4 slot can fit x1 or x4 card, but can’t fit x16 card. Finally, there are several different versions of the PCIe interface, each with different bandwidth limits, and many modern motherboards have PCIe slots of various physical sizes, and also different generations of PCIe.

Let’s start with the maximum theoretical bandwidth. A single PCIe 1.0 (or 1.1) lane can carry up to 2.5 Gb/s per second (GT/s) in each direction at the same time. For PCIe 2.0, which increases to 5Gbps, and a single PCIe 3.0 lane can carry 8Gbps.

Gigatransfers per second is the same (in this case) as gigabits per second . All versions of PCI Express lose some of their theoretical maximum bandwidth for the physical costs associated with electronic transfers. PCIe 1.* and 2.0 use 8b/10b encoding (like SATA), which results in every 8 bits of data costing 10 bits to transfer, so they lose 20 percent of their theoretical bandwidth. It’s just the cost of doing business. nine0003

The maximum transfer rate on PCI-1.0 is eighty percent of 2.5Gbps. This gives us two gigabits per second, or 250 MB/s (remember, eight bits per byte). The PCIe interface is bidirectional, so that’s 250MB/s in each direction, per lane. PCIe 2.0 doubles the bandwidth per lane to 5Gbps, giving us 500MB/s of actual data transfer per lane.

The PCIe 3.0 interface has twice the transfer rate of PCI 2.0. nine0003

And so we know that PCIe 3.0 is twice the speed of PCI 2.0, but as we saw above, the theoretical throughput of each lane is 8Gbps, which is 60 percent more than 5GT/s PCIe 2.0. This is because PCIe 3.0 and above use a more efficient encoding scheme called 128b / 130b , so the resource consumption is much less at just 1.54 percent. This means that one PCIe 3.0 slot with 8Gb/s bandwidth can send 985MB/s. It’s not exactly double 500 MB/s, but it’s close enough for marketing purposes.

This means that a PCIe 3.0 x4 (3.94 GB/s) connection has almost the same bandwidth as PCIe 1.1 x16 or PCIe 2.0 x8 (both 4 GB/s).

Modern GPUs use the x16 PCIe 2.0 or 3.0 interface. This does not mean that they always run at x16 speed. Many motherboards have multiple x16 physical slots, but fewer actual PCIe lanes. nine0003

And so, in our example on the Z87 (Haswell) or Z77 (Ivy Bridge) desktop, the processor has 16 PCIe 3. 0 lanes . There are eight more PCIe 2.0 lanes on Intel chipsets, but these are commonly used for sound cards, RAID cards, etc. (The AMD 990FX chipset includes 32 PCIe 2.0 lanes and four on the northbridge). In the Asus board above, the PCIe 3.0 slots are CPU lanes, while everyone else has to share eight PCIe 2.0 chipsets. Using a PCIe 2.0 x16 slot in x4 mode disables three PCIe 2.0 x1 slots. nine0003

So a single x16 video card will use all 16 PCI lanes with a PCI processor, but adding a GPU to the second x16 lane will disable both video card connections up to eight lanes. Adding a third GPU will cause the first card connected to x8, and the second and third cards connected to x4.

This is why many people who run multi-GPU rigs prefer Intel enthusiast architectures such as Sandy Bridge-E and Ivy Bridge-E as some Ivy Bridge-E technology processors are capable of up to forty lanes in PCIe 3.0. This is enough to run two x16 cards and one x8 card, one x16 card and three x8 cards, or one x16 card, two x8 cards, and two more x4 cards.

Is this important for performance?

Two PCIe 3.0 GPUs running at x8 each on a PCIe 3.0 motherboard have about the same bandwidth as two PCIe 2.0 GPUs running at x16 — the first set runs at 7.88 GB/s each, and the second one runs at 8 GB/s. If your motherboard or graphics card is limited to a PCIe 2.0 connection, you will be stuck due to the slower interface. nine0003

TechPowerUp showed a huge amount of PCIe performance. At the time, they were testing two powerful single-GPU cards — the AMD Radeon HD 7970 and the Nvidia GeForce GTX 680 — at x4, x8, and x16 using PCIe 1.1, 2.0, and 3.0, all on the same motherboard. This is by far the best test I’ve ever seen on PCIe bandwidth scaling. The performance summary page summarizes relative results at a glance.

As you might expect, equivalent throughput configurations perform about the same. To quote the authors of TechPowerUp: “Our testing confirms that modern graphics cards work fine at a lower bus speed, but performance degrades the bus speed. nine0043 Everything up to x16 1.1 and its equivalents (x8 2.0, x4 3.0) provides adequate gaming performance even with the latest graphics hardware, losing only 5% on average in the worst case. [emphasis added] It’s only at lower speeds that we see a dramatic drop in frame rate that would justify action.»

The most interesting part of these results is the finding that last year’s most powerful graphics cards run just fine on PCIe 2.0 x8 or even PCIe 3.0 x4. This means that three-way SLI or CrossFireX should be viable, even in x8/x4/x4, on Ivy Bridge or Haswell desktops. But even if you don’t have PCIe 3.0, you won’t miss out on great x8 performance on a PCIe 2.0 connection.

Double the bandwidth of PCIe 3.0 x16 compared to PCIe 2.0 doesn’t seem to matter much yet. Ryan Smith from AnandTech tested two Nvidia GeForce GTX Titans, the fastest single GPU cards in SLI on PCIe 3.0 and 2.0, and at best delivered a 57% performance improvement over 5760 x 1200.

So this is good news for people with old motherboards or graphics cards. If you have at least PCI Express 2.0 x8, you are unlikely to leave any hope for performance, even on the fastest cards.

Thunderbolt interface

Thunderbolt is a data interface that can pass through PCI Express and DisplayPort signals, depending on what it is connected to. The Thunderbolt controller consists of two bidirectional data channels, with each channel containing an input and an output strip. nine0003

Thunderbolt chips at each end of the cable are used in both DisplayPort 1.1a and quad-lane PCIe 2.0. Each channel is independent and can either carry DisplayPort or PCIe, but not both. Each direction in each channel has a theoretical maximum bandwidth of 10Gbps — the same as two lanes of PCIe 2.0. As discussed above, due to 8b/10b encoding, 20 percent of the theoretical PCI Express 2.0 limit is dedicated to signal overheads, so the maximum theoretical throughput of a single Thunderbolt link is 1 GB/s in each direction. nine0129

In first generation Thunderbolt, this is as fast as it gets, because each device can only access one of the two channels, and you can’t combine them. Data transfer is pretty fast, as you can send high-definition video to a DisplayPort monitor at 10 Gb/s over a single link while reading 1 GB/s from an SSD RAID.

So how much performance can you get out of a Thunderbolt connection? nine0136

Example: Gordon Ung at Maximum PC records a maximum read speed of 931MB/s when reading from RAID 0 of four 240GB SandForce SF-2281 SSDs in a Pegasus R4 chassis.

A quad-thread RAID 0 SSD will be pretty fast for a first generation Thunderbolt connection. Dual disk RAID 0 can approach the speed of individual disks, a good 6Gb/s SSD can go up to 515MB/s. A RAID 0 of two 6Gb/s SSDs can easily saturate the 10Gb/s connection available in the first generation Thunderbolt. nine0129

A very short note on PCIe SSD performance (compared to Thunderbolt)

Despite the limitations of first generation Thunderbolt, it is still a much better external storage interface than USB 3.