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PCIe 3.0 vs 4.0: 5 Key Differences and Full Comparison

PCIe 3.0 vs 4.0

PCIe 3.0 vs 4.0: 5 Key Differences and Full Comparison

The pace of technological innovation is relentless, keeping product makers on their toes and ensuring consumers always get the best of what’s available. One of the innovation fronts where this is especially true is the PCIe standard, which is why we’ve compared PCIe 3.0 vs 4.0 in detail to see which one currently reigns supreme and why.

Used for connecting high-speed components like graphics cards and solid-state drives to a computer’s motherboard, the PCIe standard has gone through several technological iterations with each successive one offering us improved performance compared to its predecessor.

PCIe 3.0 vs 4.0: Side-by-Side Comparison

With each new generation, the PCIe (Peripheral Component Interconnect Express) interface has seen improvements in speed and power efficiency, making it an even more attractive option for those looking to upgrade their systems or build new ones from scratch.

Let’s compare the side-by-side to see what really sets them apart and which one might be right for your next build.

PCIe 3.0PCIe 4.0
Transfer Rate (x16 slot)Up to 32 GB/sUp to 64 GB/s
Bandwidth (Top speed)8 GT/s per lane16 GT/s per lane
Latency250 ns125 ns
Power Efficiency8 W/GB4 W/GB
CompatibilityCompatible with most motherboardsBackward compatible but may require hardware and firmware upgrades for some systems
CostComponents are generally affordableComponents are generally more expensive

PCIe 3.0 vs 4.0: What’s the Difference?

Transfer Speed and Bandwidth

PCIe 4.0 has an insatiable appetite for data, handling up to twice the bandwidth of its predecessor, PCIe 3.0. At a throughput rate of 1 GB/s (gigabytes per second) per lane, PCIe 4.0 can move mountains of data in the blink of an eye.

And, with a maximum speed of 16 GT/s (gigatransfers per second) per lane, as well as a 64 GB/s maximum theoretical transfer speed, the PCIe 4.0 interface clearly transfers data at breakneck speeds. 

pcie 3.0 vs 4.0
PCIe 3.0 upgraded the encoding scheme to 128b/130b from the previous 8b/10b encoding.

In contrast, PCIe 3.0 has a top speed of 8 GT/s per lane and a transfer speed of up to 32GB/s. That’s still respectable but, in all honesty, it pales in comparison to PCIe 4.0’s speeds.

If you’re a gamer, a video editor, or a data scientist, you’ll appreciate the extra horsepower that PCIe 4.0 brings to the table. Whether you’re transferring large files, rendering 3D graphics, or crunching big data sets, PCIe 4.0 is currently the best we have and is sure to handle it all with ease.

Latency

While latency may not be the first thing on people’s minds when looking for PCIe interfaces, it’s an important factor to consider. In simple terms, latency is the time it takes for a data request to be completed.

So, if you’re looking for an interface that can deliver your data faster, PCIe 4.0 is the way to go. With a latency of just 125 nanoseconds, PCIe 4.0 is twice as fast as PCIe 3.0, which has a latency of 250 nanoseconds.

That may not seem like a big difference, but in the world of computing, even a few nanoseconds can make a significant impact on performance. So, whether you’re gaming, streaming, or working on complex graphics, PCIe 4.0’s lower latency can make a real difference. You sure don’t want to be held back by slow data transfer speeds or lag time, after all.

Power Efficiency

PCIe 4.0 is definitely the one to beat on the power efficiency front. With its more advanced features and higher power limits, it’s no surprise that it consumes more power than PCIe 3.0. However, the real difference lies in power efficiency.

PCIe 3.0 has a power efficiency of 8 W/GB, which is already quite impressive. But PCIe 4.0 takes it to the next level with a power efficiency of 4 W/GB, which means that it uses half as much power per gigabyte transferred, compared to its predecessor.

PCIe 4.0’s power management features also enable impressive power efficiency without compromising performance. This makes it an ideal choice for power-conscious users. PCIe 4.0’s power efficiency is also good news for data centers and other enterprise users who need to keep power costs under control.

Compatibility

PCIe 4.0 and PCIe 3.0 have some distinct variations in terms of compatibility. PCIe 4.0 devices can operate on PCIe 3.0 slots as PCIe is backward compatible, but they will only be able to reach the slower PCIe 3.0 speeds. In contrast, PCIe 3.0 is compatible with most motherboards, making it more widely accessible.

pcie 3.0 vs 4.0
In December 2017, IBM announced the first system with PCIe 4.0 slots, Power AC922.

However, if you want to use PCIe 4.0 on your motherboard, you may need to make some hardware and/or firmware upgrades. This means that while some users may have to invest in new hardware to upgrade their systems to PCIe 4.0, others can simply swap out their existing PCIe 3.0 devices.

It’s worth noting that PCIe 4.0 may also require a newer CPU and motherboard, so make sure to check your system’s specifications before making any upgrades. 

But, even though the compatibility of PCIe 4.0 is technically more limited, it’s still totally worth it if you have a newer system and want to take advantage of the increased speeds and power efficiency.

Cost

PCIe 4.0 may offer impressive speed and power efficiency, but its advanced technology comes at a cost. PCIe 4.0 components are generally more expensive than their PCIe 3.0 counterparts, making them a more costly option for those who are budget-conscious. 

This is mainly due to the increased complexity of the standard that requires more advanced and expensive hardware to achieve its impressive speeds. However, it is worth noting that as PCIe 4.0 becomes more widely adopted, the cost difference between PCIe 3.0 and PCIe 4.0 components continues to fall steadily.

As more and more manufacturers start developing products that use the newer standard, prices become more competitive and consumers benefit from better deals on hardware. Additionally, as the technology matures, it becomes easier for manufacturers to produce components at a lower cost. This makes them more accessible to a wider range of consumers and businesses alike. 

Furthermore, many believe that investing in PCIe 4.0 hardware is worthwhile due to its superior performance compared to older generations, as it allows them to maximize their system’s potential.

PCIe 3.0 vs 4.0: 5 Must-Know Facts

  1. PCIe 3.0 was released in 2010, while PCIe 4.0 was released in 2017 — a seven-year gap between the two standards.
  2. The physical link layer of PCIe 4.0 is the same as that of PCIe 3.0, meaning that no new connectors or cables are needed.
  3. The PCIe 4.0 specification also allows for devices to be plugged in and out while the system is running, just like with PCIe 3.0.
  4. PCIe 4.0 is optimized for flash storage, allowing for faster data transfers from SSDs and other flash-based storage devices.
  5. Some PCIe 4.0 devices, such as NVMe SSDs, can offer read and write speeds of up to 7000 MB/s and 5500 MB/s, respectively. That’s well below the theoretical limits, but still lightning-fast compared to traditional hard drives.

PCIe 3.0 vs 4.0: Which One Is Better? Which One Should You Choose?

When it comes to choosing between PCIe 3.0 and PCIe 4.0, the decision essentially comes down to the performance requirements of your system. With double the bandwidth and transfer speed, as well as improved power efficiency and low latency, PCIe 4.0 is a great choice for those looking to maximize their computing power. 

As we’ve seen, PCIe 4.0 is capable of transferring 2 Gigs of data per second per lane, while PCIe 3.0 manages a modest 1 GB/s per lane — half the throughput of PCIe 4.0. If you’re a gamer or PC builder, you sure don’t want to be held back by slow data transfer speeds.

PCIe 4.0 can handle the heaviest workloads with ease, giving you the speed and performance you need to get the job done quickly and efficiently. PCIe 4.0 is, therefore, your best bet if you want to get the most bang for your buck; but remember to consider your system’s needs before making a final decision.

Frequently Asked Questions

How does PCIe 4.0 compare to PCIe 3.0?

PCIe 4.0 offers twice the bandwidth of PCIe 3.0, which means it can transfer data at up to 16 GT/s per lane, while PCIe 3.0 can transfer data at up to 8 GT/s per lane. PCIe 4.0 also supports more power delivery, improved signaling, and lane margining.

What are some of the devices that utilize PCIe 4.0 on a PC motherboard?

Currently, the most common components that are using PCIe 4.0 are GPUs, PCIe storage devices, and NVMe SSDs.

Can I connect a PCIe 3.0 device to a PCIe 4.0 slot?

Absolutely, yes! PCIe 4.0 is backward compatible with older PCIe versions. However, if you use a PCIe 4.0 device on a PCIe 3.0 slot, it will only run at PCIe 3.0 speeds, so do take note of that.

Are there any other older versions of PCIe?

Yes, there are earlier versions of PCIe, including PCIe 1.0, 2.0, and 2.1. These versions are older and slower than PCIe 3.0 and 4.0, but are still supported by some devices and motherboards.

What does the future of PCIe look like?

Even though PCIe 4.0 is the latest and most powerful iteration of the PCI Express standard, it won’t be the last — PCIe 5.0 is already in the works and is expected to be launched sometime later this year. PCIe promises even faster speeds and improved power efficiency.

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