What is PCIe 5.0, and how is it different from previous generations?

PCIe 5.0 is the latest consumer-available PCIe serial expansion bus standard iteration. PCIe stands for Peripheral Component Interconnect Express, and its first iteration was introduced in 2003 as an upgrade over older PCI, PCI-X, and AGP standards. The name can also be written as PCI Express or PCI-e. Over the past decade, PCIe has become the most common motherboard interface for various devices, from graphics cards to SSDs and Wi-Fi cards. Each PCIe revision doubles the data throughput of the previous generation, and this is the case with the PCIe 5.0 specification as well.

The standard is specified by the PCI-SIG, or Peripheral Component Interconnect Special Interest Group, which is a working body of over 800 companies that defines the specifications of the standard for certification and compatibility. With all that said, let’s dive into everything you should know about PCIe 5.0, from differences over the previous standard, to exactly what devices support it and whether you should upgrade your system to reap its benefits.

PCIe 5.0 versus PCIe 4.0

A major upgrade over the PCIe 4.0 standard, PCIe 5.0 doubles the maximum data throughput from 31 gigabytes per second (GB/s) to roughly 63 GB/s. While technically, the PCIe 5.0 specification allows for up to 32 lanes, no consumer-facing CPUs, motherboards, or devices offer many lanes per slot.

At the time of writing, apart from platforms like the motherboards and CPUs, there are very few devices you can buy that are PCIe 5.0 certified – there are only a few M.2 NVMe SSDs. There are no graphics cards, either.

Currently, the fastest PCIe 5.0 M.2 NVMe SSD sequential read speeds are rated around 12,400 MB/s and write speeds closer to 11,800 MB/s. Compare this to the rated 7,450 MB/s read and 6,900 MB/s write speeds of the fastest PCIe 4.0 M2 NVMe SSDs, and we see a major difference.

However, random write and read speeds don’t see that much of an upgrade from the previous generation. The fastest PCIe 5.0 M.2 NVMe SSDs are rated at 1.5 million input/output operations per second (IOPS). Compare this to some of the fastest PCIe 4.0 M.2 SSDs, which are rated at about 1.4 million IOPS for random read/write speeds, and you can see the difference is not that significant.

Should you upgrade to a PCIe 5.0 setup?

As we can see from the above figures, the biggest differences are primarily seen in sequential read/writes, with barely any differences in random read/writes. What does this mean to you, the consumer? Suppose you aren’t a content creator or professional who is decoding and encoding massive files. Sequential speeds aren’t as important as random speeds – which are more important for other usage scenarios like gaming.

The price difference between a PCIe 5.0 M.2 SSD and a PCIe 4.0 M.2 SSD is usually double. The overall price difference in your PC’s configuration will also be significant if you upgrade from an older CPU and motherboard combination that only supports PCIe 4.0 to one that supports PCIe 5.0.

Newegg / Crucial

With the speed boost and power draw requirements of actually running them at the highest speeds, PCIe 5.0 SSDs also end up requiring heatsinks and, in some cases, active cooling solutions. This increases the cost significantly as well.

Thus, the answer to the question – should you upgrade – depends on whether faster storage is an advantage in your day-to-day use cases and whether that advantage is worth the cost difference. The answer is no for most people, as the cost is prohibitive.

PCIe 5.0 SSDs you can buy

Currently, only a few SSDs you can buy are PCIe 5.0-rated. Going through Newegg, there aren’t too many brands available. A popular recommendation is the Corsair T700. Its 1TB variant was priced at $159.99. Compare that to the popular PCIe 4.0 Samsung 980 Pro, with its 1TB variant priced at $59. There are options, but they’re sparse and overly expensive right now.

Newegg / Crucial

PCIe 5.0 compatible CPUs you can buy

As you’d expect, even if your CPU supports PCIe 5.0 devices, you can only use such devices if your motherboard also supports it. In some cases, while a single x16 slot supports PCIe 5.0, the M.2 slots may not support it. In other cases, there may be two PCIe 5.0 x16 slots, but if you place a PCIe 5.0 M.2 SSD in one of the two slots, the other slot will only work in x8 mode.

Intel’s 12th and 13th Gen Core processors are compatible with PCIe 5.0 devices, supporting up to 20 lanes in total.

AMD 7000 series processors using the AM5 socket are compatible with PCIe 5.0 devices and support up to 28 lanes.

What’s next for PCIe? (PCIe 6.0)

As we mentioned, each revision of the PCIe specification doubles the data throughput. The final PCIe 6.0 specification was released in 2022, just 3 years after the PCIe 5.0 specification. The revisions are coming almost faster than hardware can keep up with it. To put that in perspective, the final PCIe 5.0 specification was released in 2019, the final PCIe 4.0 specification in 2017, and the final PCIe 3.0 specification in 2010.

With PCIe 6.0, transfer rates per lane go up to 64 GT/s, and data throughput goes up to 121 GB/s across 16 lanes. The first PCIe 6.0 CPUs, motherboards, and devices will hit the market in 2024. The preliminary PCIe 7.0 specification has already been released, with the final specification expected in 2025. It doubles the data throughput up to 242 GB/s.

How does PCIe work?

The motherboard on your desktop or laptop features multiple PCIe slots. These expansion slots let you connect discrete hardware to your PC over the PCIe interface. There are usually several types of PCIe slots, defined by their ability to fit a particular size of the device and the number of data lanes the slot supports.

A PCIe device that connects to a motherboard is usually called a card (e.g., capture card, graphics card, sound card, or Wi-Fi card) but can also be called a drive in the case of SSDs. To be noted here is that the very common M.2 storage slot supports the PCIe 3.0 (and newer), USB 3.0, and SATA 3.0 storage interface standards, and most modern SSDs use the NVMe specification for PCIe SSDs.

PCIe cards and slots are named based on dimensions (also known as their mechanical size) and supported number of lanes (also known as electrical or logical interface). Standard mechanical sizes are listed as x1, x4, x8, and x16. A card with a smaller size can fit a larger sized slot (x4 card can fit in an x16 slot), but a larger card cannot fit a smaller slot (x16 card cannot fit in an x4 slot)

Confusingly enough, lanes are also defined using ‘x’, and common lanes are x1 (1 lane), x4 (4 lanes), x8 (8 lanes), and x16 (16 lanes). Listed on the motherboard or PC’s specifications page, you will see terms like PCIe 5.0 x16 slot – which essentially means it’s a PCIe slot that supports the PCIe 5.0 standard and cards of the x16 size. If nothing else is written alongside, it implies that the slot can use the maximum number of lanes supported by the device or standard – usually x16 or 16 lanes. In many cases, motherboards include older legacy slots with fewer lanes, i.e., PCIe 4.0 x16 (x4 mode), where despite the PCIe 4.0 standard supporting up to 16 lanes, only 4 lanes can be used on the slot.

Throughput is calculated by multiplying the transfer rate per lane with encoding overhead by the number of lanes. Unfortunately, the transfer rate is usually written in giga transfers per second (GT/s) and throughput in gigabytes. Transfers per second do not consider encoding the data, and thus you will have to multiply by the encoding overhead to get gigabits per second (Gb/s). The encoding overhead for both PCIe 4.0 and PCIe 5.0 is 128b / 130b.

To calculate gigabytes per second (GB/s), you must divide the gigabits per second by 8 (as 8 bits make a byte). This means if PCIe 4.0 has a maximum transfer rate per lane of 16 GT/s, you multiply by encoding overhead of 128 bits / 130 bits, divide by 8 bits per byte, and multiply by 16 (number of lanes), to get a maximum throughput of 31.508 GB/s.