PCIe 3.0 VS 2.0: What are the differences and similarities?

Aaron Paul updated on Nov 11, 2022 to Knowledge Center

PCIe (PCI Express) slots in a computer allow you to add additional cards. While they are most commonly associated with adding graphics/video cards to a computer, they are used for many different purposes. Today, PCIe is used for many things, such as adding a sound card, Lan card, WIFI cards, etc.

However, not all PCIe slots are the same. Today, technology has evolved, and PCIe has gone up to 4.0 and 5.0. However, today, we're going to talk about its previous gen versions of PCIe 3.0 and 2.0. In this article, we'll explore their differences and similarities. So, let's dive right into it.

What Is PCIe?

PCIe, abbreviated from Peripheral Component Interconnect Express, is a standard bus for expansions in any computer. It's also defined as a serial computer expansion bus, as it allows you to interconnect additional devices into a computer's motherboard.

Most commonly, PCIe expansion slots are used for the add-in graphics card, SSD storage devices, Wi-Fi adapters, and other sorts of expansions. While PCIe is generally faster than its predecessors, like PCI, it has various uplifts from its earlier versions as well.

In fact, in June 2022, it was announced that PCIe 7.0 is officially in the works. However, we can expect that version to only become a standard in the next 5-6 years, as that's how long it usually takes to pass inspections, etc.

The latest PCIe versions supported by AMD's Zen 4 Processors and Intel's 13th Gen processors are up to 5.0. However, the most common standard in computers around the globe today happens to be its 3.0 version.

That brings us back to today's topic and the abilities of PCIe 3.0 vs. 2.0, which have been the standard for a good number of years. It wasn't until 11th Gen Intel Processors and Zen 3 by AMD that PCIe 4.0 became the standard. That's why PCIe 3.0 and 2.0 are still very relevant today.

PCIe History

PCIe 1.0 was introduced back in 2003. It had a speed of 2.5 GT/s transfers per lane. However, each one differed from the other. It wasn't until 2007 when PCIe 2.0 came into play and almost doubled that amount with 5.0GT/s transfers per lane.

Then in 2010, PCIe 3.0 came along and brought an 8.0 GT/s rating alongside it. That's why it has been the standard for PCIe devices for well over 10 years. But, before PCIe 3.0 became standard, PCIe 2.1 was introduced in 2009.

Despite having the same transfers per lane, it saw a little uplift from its predecessor. The only uplift from 2.0 was better support, serial bus management, and troubleshooting abilities compared to 2.0. but in November of 2010, PCIe 3.0 officially took over with better speeds and support.

PCIe 3.0 vs. 2.0 Differences

The similarities between PCIe 3.0 and 2.0 aren't that many. In fact, the reason they are different is because of their vastly different development and purposes. But, to help you understand just how different the two are, here's a table:

Features PCIe 2.0 PCIe 3.0
Transfers per lane 5.0 GT/S 8.0 GT/S
PCIe x1 Throughput 0.500 GB/s 0.985 GB/s
PCIe x2 Throughput 1.000 GB/s 1.969 GB/s
PCIe x4 Throughput 2.000 GB/s 3.938 GB/s
PCIe x8 Throughput 4.000 GB/s 7.877 GB/s
PCIe x16 Throughput 8.000 GB/s 15.754 GB/s

As you can see, the difference isn't only in different lanes but also in a variety of speeds. That's why it's important to understand that even though there are these differences, both of these are backward compatible.  

But, a PCIe 2.0 card on PCIe 3.0 slot will perform only to the best of its abilities, not according to the platform speed.

PCIe 3.0 vs. 2.0 Similarities

While there are certain differences between them, both of this PCIe. Use the same 1x, 2x. 4x, 8x, and 16x interfaces. However, as mentioned in the section before, the key difference is bandwidth speed.

But, once again, it's important to understand that even though PCIe 3.0 devices will be backward compatible with 2.0, they'd be limited by the bandwidth of the previous platform.

On the contrary, PCIe 2.0 devices will be forward-compatible with PCIe 3.0 but will only work at their own speeds.

Frequently Asked Questions

This section will find other frequently asked questions about PCIe 3.0 or 2.0. So, see if you can find the answers.

1. Will a PCIe 2.0 work in a PCIe 3.0 slot?

Yes, it will. As mentioned before, PCIe devices are usually both backward and forward-compatible. Therefore, any PCIe 2.0 device will work with PCIe 3.0 slot, but it'll only operate at its own max speed.

2. Is PCIe 2.0 a bottleneck?

Depends on the device you're using in it. It'll surely be a bottleneck if you're using a PCIe 3.0 or 4.0 card in a PCIe 2.0 slot. Simply because the 2.0 slot doesn't have enough bandwidth to make those cards run at full speed.

3. Does PCIe 2.0 work with NVME?

While PCIe 2.0 doesn't have a direct connection to NVME or M.2 devices, you can find adapters that allow you to connect these storage devices in a PCIe 2.0 slot.

4. Is PCIe 3.0 enough for gaming?

One would say it's outdated, considering it's 2022, and the technology was released in 2010. Today, PCIe 4.0 is the standard, and PCIe 5.0 is on the horizon. So, it's better to upgrade in 2022.

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