In this post, we will talk about the computer data transfer bus PCI Express, also known as PCI-E, this is an interface for connecting various devices to a computer. And let’s talk about PCI-E in the context of different generations of this interface – the current 3.0 and the relatively new 4.0. Why relatively new? There is already PCI-E generation 5.0, which appeared in 2019. And it is promised in this, 2021, the emergence of generation 6.0. But even PCI-E 5.0 is just an approved specification, a crude standard that hasn’t been implemented yet. In fact, only the PCI-E 4.0 generation is implemented on modern computer hardware, and even then, it is implemented weaker than PCI-E 3.0. The third generation is still relevant, it is very often found on modern hardware. After all, the implementation of the fourth generation sometimes significantly increases the cost of devices.
PCI Express 3.0 vs 4.0: what’s the difference between these generations? Should you pay extra for PCI-E 4.0 today?
PCI Express 3.0 vs 4.0: differences
PCI Express: lines and generations
So, friends, the PCI-E bus for connecting various devices to the computer video cards, high-speed SSD NVMe drives, sound cards, network adapters, Wi-Fi adapters, various adapter controllers that convert PCI-E to other interfaces and connection connectors ( USB, SATA, M.2), profile devices such as POST-cards for diagnostics of motherboards, etc.
PCI-E has a different implementation of connection connectors, traditionally these are expansion slots on the motherboard. Slots can have a different number of connection lines x2, x4, x8, x16, x32, each line has its own bandwidth, and the more lines, the greater the overall slot capacity. The standard implementation of PCI-E slots on a motherboard is 2 x16 slots (long slots) and several x1 slots (short slots).
Slots with 32 lines on regular PC motherboards are extremely rare. Slots can work conditionally: if a device is installed in one of them, the second works in the mode of a reduced number of lines. For example, if a video card is installed in one x16 slot, the second x16 slot operates in x8 or x4 mode. Any device with the same or fewer PCI-E lanes can be plugged into a slot on a motherboard with the same or more lanes. You cannot connect only a device with more lines to a slot on a motherboard with fewer lines.
And so, friends, PCI-E lanes are one characteristic that determines the bandwidth of the connection. And there are versions, they are also PCI-E generations. The newer the generation, the greater its bandwidth for each of the lines. And, accordingly, the greater the bandwidth of the total number of slot lines on the motherboard.
PCI-E appeared in 2003, this was its first generation. In 2007, the PCI-E 2.0 generation appeared. In 2010, the PCI-E 3.0 generation, and in 2016, PCI-E 4.0. With each PCI-E generation, the bandwidth per lane has increased – starting from 250 MB / s in the 1.0 generation, in the 6.0 generation it reached an incredible 7.877 GB / s. Let’s take a look at the evolution of PCI-E in a comprehensive version and lane bandwidth table.
Bandwidth Table of PCI Express 3.0 vs 4.0: x2, x4, x8, x16
|PCI-E х1||PCI-E х2||PCI-E х4||PCI-E х8||PCI-E х16|
|PCI-E 1.0||0.25 GB / s||0.5 GB / s||1 GB / s||2 GB / s||4 GB / s|
|PCI-E 2.0||0.5 GB / s||1 GB / s||2 GB / s||4 GB / s||8 GB / s|
|PCI-E 3.0||0.984 GB / s||1.97 GB / s||3.94 GB / s||3.94 GB / s||15.8 GB / s|
|PCI-E 4.0||1.969 GB / s||3.94 GB / s||7.88 GB / s||15.75 GB / s||31.5 GB / s|
|PCI-E 5.0||3.938 GB / s||7.88 GB / s||15.75 GB / s||31.51 GB / s||63.02 GB / s|
|PCI-E 6.0||7.877 GB / s||15.75 GB / s||31.51 GB / s||63.02 GB / s||126.03 GB / s|
The bandwidth of each new generation is approximately double that of the predecessor generation. Here’s what else is important to know about PCI-E generations:
- The newer generation is compatible with the older generation (theoretically, in practice, sometimes there are problems). For example, graphics cards, NVMe SSDs and other PCI-E 4.0 devices will work with a PCI-E 3.0 motherboard. Unless, of course, in the case of NVMe SSDs, there are no compatibility issues in terms of the M.2 slot , support for NVMe SSD technology and processor limitations (only for AMD) ;
- For graphics cards, NVMe SSDs and other devices to work on the newer PCI-E generation, both they and the motherboard must support it. Those. if you have a PCI-E 4.0 video card, then the motherboard must also have PCI-E 4.0. And if you have a PCI-E 3.0 SSD, then the motherboard should also have PCI-E 3.0. If a device has an older generation, it will be limited by the bandwidth of the older generation. This is how, for example, the linear speed of reading and writing data of SSD NVMe Samsung 970 EVO Plus differs in the conditions of PCI-E 3.0 and 2.0. The speed potential of a PCI-E 3.0 x4 drive in PCI-E 2.0 mode rests on the ceiling of the PCI-E 2.0 x4 interface and cannot exceed 2000 Mb / s.
PCI Express 3.0 x4 vs 4.0 x4 and PCI Express 3.0 x16 vs 4.0 x16
Now let’s look separately at the considered PCI-E 3.0 and 4.0 generations. And let’s just look at their x4 and x16 lines. It is these lines that are of interest to us first of all, because two devices work with them, for which the PCI-E generation is significant – SSD drives, mainly using x4, and video cards, mainly using x16.
|PCI-E х4||PCI-E х16|
|PCI-E 3.0||3.94 GB / s||15.8 GB / s|
|PCI-E 4.0||7.88 GB / s||31.5 GB / s|
In any case, the numbers are impressive, but what does the difference between PCI Express 3.0 and 4.0 really mean? From the start, we can only give a clear answer like this:
|PCI Express 3.0 or 4.0 – the difference is only important for powerful gaming graphics cards and high-speed NVMe SSDs with PCI-E connectivity. For any other device today, the PCI-E 4.0 generation is not needed.|
But how much PCI-E 4.0 is needed for video cards and SSD PCI-E, and whether it is needed at all, taking into account their cost in today’s realities – let’s figure it out.
Pci Express 3.0 Vs 4.0: difference for graphics cards
The difference between PCI Express 3.0 and 4.0 in the performance of video cards can only be said for games, there is such a difference, but today it is insignificant. If a PCI-E 4.0 graphics card works in different PCI-E 3.0 and 4.0 modes, the latter will have a performance gain of 1-2% in most games. In some games, the gain may be slightly higher – up to 5%. PCI-E 4.0 for video cards is more likely a reserve for the future, in particular, when the games themselves learn to use the enormous bandwidth of this interface generation.
But is it worth overpaying now for the future, or living with today’s realities, let’s figure it out by tracking the approximate cost of various powerful PCI-E 3.0 and 4.0 video cards in order of their rating in the UserBenchmark benchmark service?
Consider the twenty most productive video cards according to this benchmark.
|Ranking place||Performance||Video card||Generation PCI-E|
|1||230%||Nvidia RTX 3090||PCI-E 4.0|
|2||207%||Nvidia Quadro RTX A6000||PCI-E 4.0|
|3||204%||Nvidia RTX 3080||PCI-E 4.0|
|4||190%||AMD RX 6900 XT||PCI-E 4.0|
|5||188%||Nvidia Titan RTX||PCI-E 3.0|
|6||177%||Nvidia Quadro RTX 8000||PCI-E 3.0|
|7||173%||Nvidia Quadro RTX 6000||PCI-E 3.0|
|8||171%||Nvidia RTX 2080 Ti||PCI-E 3.0|
|9||161%||AMD RX 6800 XT||PCI-E 4.0|
|10||160%||Nvidia Titan V||PCI-E 3.0|
|11||153%||Nvidia RTX 3070||PCI-E 4.0|
|12||144%||Nvidia Titan Xp||PCI-E 3.0|
|13||138%||Nvidia RTX 2080 Super||PCI-E 3.0|
|14||136%||Nvidia GTX 1080 Ti||PCI-E 3.0|
|15||135%||Nvidia Quadro RTX 5000||PCI-E 3.0|
|16||134%||Nvidia Titan X Pascal||PCI-E 3.0|
|17||134%||AMD RX 6800||PCI-E 4.0|
|18||131%||Nvidia RTX 3060 Ti||PCI-E 4.0|
|19||129%||Nvidia Quadro P6000||PCI-E 3.0|
|20||125%||Nvidia RTX 2080||PCI-E 3.0|
As you can see, the top of the rating is occupied by PCI-E 4.0 video cards, but in the entire twenty, there are PCI-E 3.0 video cards, which are more productive and more expensive. If you are ready to pay more for a video card, of course, consider purchasing it with a PCI-E 4.0 interface. For example, AMD RX 6800-XT PCI-E 4.0, will be more productive, but cheaper than the veteran PCI-E 3.0 Nvidia GTX 1080-Ti. now it is not found on the primary market. And AMD RX 6800-XT will be cheaper and more productive than Nvidia RTX 3070 with PCI-E 4.0.
If you are not ready to spend more on a video card, take it from PCI-E 3.0, possibly from the secondary market. And leave the future for the future.
See also How To Connect Extra Fans To Motherboard.
PCI Express 3.0 and 4.0: Difference for NVMe SSD
The increased bandwidth of the PCI-E 4.0 generation has opened the way for SSDs to go beyond the limitations of PCI-E 3.0. But many PCI-E 4.0 SSD manufacturers have made little use of this opportunity. There is SSD PCI-E 4.0, the maximum read and write speed of which does not exceed even the bandwidth of PCI-E 3.0, and, obviously, the implementation of PCI-E 4.0 in such drives is just a marketing ploy.
There are PCI-E 4.0 SSDs, which partially take advantage of PCI-E 4.0 capabilities they can read data at a maximum speed of 5000-6000 MB / s, but write data at a maximum speed of up to 3000 MB / s. All this, friends, because the bandwidth of the interface for PCI-E SSD is not enough, the drive itself must be able to realize the bandwidth potential, and this depends on the type of flash memory, controller, and write caching technology.
But, as with video cards, in the case of PCI-E SSDs, one cannot say that for them massively PCI-E 4.0 is an interface for growth. Several storage manufacturers have done an excellent job of harnessing the potential of PCI-E 4.0. Fastest today are select NVMe PCI-E 4.0 Intel Optane SSDs on 3D Xpoint memory. Premium such drives can read and write data at a maximum speed of 7200 MB / s.
These are expensive drives, in any case, there is no need for an ordinary user to buy them. The fastest PCI-E 4.0 SSD on flash memory today is the Samsung 980 PRO. The Samsung 980 PRO terabyte drive can read and write data at a maximum speed of 7000 MB / s and 5000 MB / s, respectively. Samsung 980 PRO is the only drive for which it is worth considering buying a motherboard with PCI-E 4.0.
The Samsung 980 PRO is Samsung’s first PCI-E 4.0 NVMe SSD and is the sibling of the Samsung 970 EVO Plus, the fastest PCI-E 3.0 SSD. Let’s compare the maximum speeds and prices of these drives.
|Storage volume||Connection interface||Maximum read speed||Maximum write speed|
|Samsung 970 EVO Plus|
|250 GB||PCI-E 3.0||3500 Mb / s||2300 Mb / s|
|500 GB||PCI-E 3.0||3500 Mb / s||3200 Mb / s|
|1 TB||PCI-E 3.0||3500 Mb / s||3300 Mb / s|
|2 TB||PCI-E 3.0||3500 Mb / s||3300 Mb / s|
|Samsung 980 PRO|
|250 GB||PCI-E 4 .0||6400 Mb / s||2700 Mb / s|
|500 GB||PCI-E 4 .0||69 00 Mb / s||5000 Mbps|
|1 TB||PCI-E 4 .0||7 000 MB / s||5000 Mbps|
|2 TB||PCI-E 4 .0||7 000 MB / s||5 1 00 Mb / s|
The Samsung 980 PRO is 33-34% more expensive than the Samsung 970 EVO Plus, and the 2 TB model is 42% more expensive.
Now let’s take a look at the synthetic benchmarks of these two drives and compare their 500GB models. In the CrystalDiskMark tests, the Samsung 980 PRO falls short of the read and write speeds declared by the manufacturer. But overall, its sequential speed scores with different queue depths (SEQ1M Q8T1 and SEQ1M Q1T1 tests) are significantly higher than the Samsung 970 EVO Plus. In the multithreaded test of random processing of small data (RND4K Q32T16), the Samsung 980 PRO has a slight advantage, but it does exist. In a single-threaded random small data processing test (RND4K Q1T1), the Samsung 980 PRO read data faster but wrote it faster than the Samsung 970 EVO Plus.
But, friends, all this is synthetic, in the realities of working with a computer of an ordinary user, even the maximum speeds of an NVMe SSD PCI-E 3.0 will be prohibitive.
If you do not frequently copy data, if you do not work with virtual machines, if you do not carry out other operations on your computer, where the potential of a PCI-E 4.0 SSD can be revealed, the capabilities of a good PCI-E 3.0 SSD like the Samsung 970 EVO are more than enough. Plus. In the operation of the operating system, in games, in video rendering, the PCI-E 4.0 SSD will not have any advantage over the PCI-E 3.0 SSD.
What else speaks in favor of PCI-E 3.0 SSD? The market for SSD PCI-E 4.0 is still scarce today, but on the market for SSD PCI-E 3.0 we will find a huge variety of models, including in the budget niche.
PCI Express 3.0 vs 4.0: difference of motherboards
Prices for motherboards with PCI-E 3.0 and two M.2 PCI-E slots start about100 dollars. But, for example, for a PCI-E 3.0 motherboard on the Intel Z490 chipset, which provides for overclocking, you will have to pay more.
Prices for motherboards PCI-E 4.0 with two M.2 PCI-E slots start about 150 dollars. But, interestingly, for a motherboard on an advanced Intel Z590 chipset with the ability to overclock and a bunch of bells and whistles, you will also have to pay more $.
So, my friends, the motherboard is perhaps the only device that definitely has a reason to buy today with the PCI-E 4.0 interface.
Well, let’s summarize: PCI Express 3.0 vs 4.0: is there a difference or not? There is a difference, but in the case of a video card, it is insignificant, in the case of an NVMe SSD not necessary for everyone, for ordinary users definitely not. But the difference in the price of video cards and NVMe SSDs with PCI-E 3.0 and 4.0 is in most cases very significant. There is absolutely no need to overpay for these devices now, over time they will become cheaper. But you can take a sensible motherboard with PCI-E 4.0 right now. Thus, you will provide yourself with a chance in the future to purchase a video card or NVMe SSD with PCI-E 4.0, when these devices will be more affordable and it will be expedient for you personally to purchase them.