PC Gear Lab

PCIe 3.0 vs 2.0 – Compared and Explained

Many people already have an idea about what the PCIe standard entails. But to reiterate for those who are not too familiar, the standard allows the connection of additional peripherals to your motherboard.

If you have ever heard someone talking about installing a graphics card or a sound card on a modern motherboard, chances are a PCIe slot was meant to be used.

The entire standard for PCI is developed and maintained by PCI-SIG and over the years they have been coming up with newer and better ways to improve data transfer efficiency.

In this article, we look at PCIe 3.0 vs 2.0. These standards have been available for a while now with the newer one between the two is almost a decade old.

While their physical appearance might be similar, these two differ mostly in speed or data transfer rate and bandwidth.

What are Their Similarities?

Before charging headfast into PCIe 3.0 vs 2.0, let us first see the places where these two standards match up. This may provide some perspective into what each generation is capable of. We’ll look at these differences in more detail as we go along.

PCIe slots on a motherboard
PCIe Slots from different generations have the same physical connectors. Source: tomshardware.com

Physical Size

PCIe 3.0 and 2.0 are part of the PCIe standard although they are two different generations of the same. Their connectors on both the devices and the slots are physically similar.

This means that if you have a motherboard that is running on the older generation PCIe 2.0 slots and you have newer generation PCIe 3.0 cards, you can still install them on the board and they will work just fine.

Compatibility

While PCIe 2.0 and 3.0 slots and devices can be used together, both these generations happen to be compatible with those that preceded them as well as those that came after them.

This means that PCIe 2.0 is compatible with PCIe 1.1 and equally PCIe 3.0 is compatible with PCIe 4.0.

Also Read: Can You SLI Two Different GPUs?

PCIe 3.0 vs 2.0

Now that we know a few of the things that make these standards similar, let’s take a finer look at them on a head-to-head comparison.

No doubt that these are both standards for connecting high-speed devices, and, if you assumed that with the bump-up in generation from PCIe 2.0 to PCIe 3.0 you’d get some major improvements then you were right.

PCIe 2.0

Specifications for PCIe 2.0 were released in 2007. At the time, the slots and devices that came out supporting this offered some of the fastest peripheral device speeds in the market.

With PCIe 2.0, users got significant performance improvements from PCIe 1.1 and it showed not only in the numbers but also in real-life usage.

Since the PCIe standard comes in configurations of X1, X4, X8, and X16, about the total number of lanes that the slots supported, a single PCIe 2.0 lane could support transfer speeds of up to 500 MB/s in both directions.

This was about double the speeds that were seen in the older PCIe version.

Also Read: What does PCIe x16 Mean?

PCIe 3.0

Three years after PCIe 2.0 came out, a new generation of PCIe was again released, PCIe 3.0. As per the specification, this standard had a lot more to offer than the older standard, and users were glad to learn that they could still use their older motherboards with the newer PCIe 3.0 devices.

As compatibility was the norm, users became more and more aware of the radical changes in the PCIe standard and as such, they saw a means to future-proof their systems.

The newer standard meant that they could get newer devices that could last them long until the next generation came out and even then, still be just as useful.

Let’s now divert from the scenic route and see the areas where the generations differ.

A PCIe 3.0 Slot
A PCIe 3.0 slot on a motherboard lets you utilize higher bandwidths for data transfers. Source: guru3d.com

Lane Speeds

When PCIe 3.0 was announced, many keen users noted immediately that the maximum bandwidth on each lane between itself and the older PCIe 2.0 had doubled.

As seen, PCIe 2.0 was doing about 500MB/s in bandwidth. This translated to about 8GB/s for the X16 connector in this generation. Unapologetically, PCIe 3.0 disrupted that and took off at a staggering 16GB/s for the largest 16-lane cards and slots.

This meant that each lane could typically transfer data much faster in PCIe 3.0 as compared to PCIe 2.0. For a time when computers were exponentially improving, a PCIe 3.0 card would have been the better candidate for most power users with the need for newer cards.

Also Read: Motherboard vs Circuit Board

Encoding

Before data is transmitted, it needs to be packaged in a way that helps the receiver understand what it’s receiving and how to handle it.

PCIe 2. Makes use of an 8b/10b encoding system. What this means is that for every 10 bits that are transmitted from source to destination, 8 bits are the data and the remaining 2 bits (20% of the total transmission) are considered overhead.

With PCIe 3.0, the data is encoded using a 128b/130b encoding system. This significantly reduces the overhead; therefore, more data can be transmitted with each cycle.

Overall Performance

As you’d expect, the third generation of PCIe devices and cards offers the best performance when compared to the second generation PCIe 2.0 implementation.

At almost double the bandwidth, you are likely to see some significant differences when doing some very heavy tasks.

Independent testers have compared both generations in terms of gaming and found that there weren’t that many differences in performance.

A difference in about 2-5 fps between the two is not too much of a problem, especially when considering the price of a board with PCIe 3.0 cards compared to PCIe 3.0 cards.

PCIe 3.0 vs 2.0
There are minimal performance differences between PCIe 2.0 and 3.0 when it comes to tasks like gaming. Source: overclock.net

Extended Use

Both PCIe 2.0 and 3.0 are compatible with all other generations of the PCIe standard, however, for users hoping to get the best performance over time from their system and keep up with the trends in the PCIe arena, it is best to go with a PCIe 3.0 motherboard over a PCIe 2.0 motherboard for several reasons.

The first is because the third generation is much faster, you get to enjoy better speeds. High transfer rates mean that for applications like video rendering or gaming, you get better performance from PCIe 3.0.

Also, because newer devices that come out are much faster, if you have a motherboard with PCIe 2.0 slots, you will end up not fully utilizing some of your newer generation cards.

The slot will bottleneck the card’s performance hence you end up underutilizing it.

All this goes to show that when it comes to computers, sometimes newer is always better.

Conclusion

After this lengthy discussion about PCIe 3.0 vs 2.0, we have seen that with the upgrade in generations, we also get an increase in the performance of the component.

PCIe components are compatible, meaning that regardless of what generation you have, whether a 2.0 or a 3.0, you will still be able to use the different slots and devices together without much of a hassle.

One thing you’ll need to note, however, is that if you chose to mix PCIe 2.0 and 3.0 devices and slots, the overall setup will work at the lowest common speed. Nevertheless, both PCIe 2.0 and 3.0 are still shipped together on the same motherboard.

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