Pci-E x8: The difference between PCIe x1, x4, x8, x16- DuroPC Industrial Computers — Mitspielen — Vampire Live in München

The difference between PCIe x1, x4, x8, x16- DuroPC Industrial Computers

The difference between PCIe x1, x4, x8, x16

In a previous blog post, we covered the difference between PCI and PCI-X. The response to the post was enthusiastic, and we were asked to write a complementary post explaining the difference between PCIe x1, x4, x8, x16. We are always happy to answer customers’ questions (feel free to contact us with your questions regarding industrial computers).

The short answer is:

‘PCIe x1’ connections have one data lane
‘PCIe x4’ connections have four data lanes
‘PCIe x8’ connections have eight data lanes
‘PCIe x16’ connections have sixteen data lanes

The long answer:

The more data lanes in a connection, the more bandwidth between the card and the host. However, there is usually a cost increase incurred with higher lane counts.

Photo from http://blog.savel.org/2005/05/31/pci-express-cards/

PCIe is an updated version of the PCI protocol. Similar to PCI/PCI-X interfaces, PCIe was developed for peripheral component interconnection. PCIe differs from PCI/PCI-X in several ways, but this blog won’t cover most of those differences. However, one key difference will allow us to better understand the differences between the variations of the PCIe protocol (x1, x4, x8, x16 and x32). That key difference is ‘parallel’ versus ‘serial’ data transmission.

In PCI and PCI-X architecture, all of the cards share parallel data lines to and from the host. Differences between card-speeds and slot-types regularly result in throttled data speeds.

In the PCIe architecture, Each card has it’s own dedicated serial data connections (lanes) to the host. This allows each card connection to achieve a bandwidth independent of other cards that may be active in the system. The number of lanes are indicated by the suffix of the PCIe protocol (×1, ×4, ×8, ×16, ×32). Each lane is capable of speeds from 250-1969 MB/s, depending on the version of the PCIe protocol (v1. x, v2.x, v3.0, v4.0).

PCIe cards can always operate in PCIe slots with the same or more lanes than the card. For example, an x8 card can operate in a slot with x8, x16, or x32 lanes. Similarly, an x1 card can operate in any PCIe slot.

caveat:

Sometimes, a PCIe slot operates with fewer data lanes than the mechanical slot-type indicates. For example, sometimes a motherboard manufacturer will use an x16 mechanical slot even though the data connection is only x8. In these cases, the higher-bandwidth card still may work (for example, an x16 card in an x16 slot with only x8 connection), if the card doesn’t require that extra bandwidth. The following image shows the PCI connections of the motherboard used in DuroPC’s RAC355. Notice ‘SLOT 1/5’ are PCIe x16 slots but only have an x8 connection. Similarly, notice how ‘SLOT 7’ uses an x8 slot but only has an x4 connection. (Click the image to see a larger version.)

Tagged on: PCI express, PCIe, PCIe x1, PCIe x16, PCIe x4, PCIe x8

PCIe 3.

0 x8 vs. x16: Does It Impact GPU Performance? | GamersNexus

This is a test that’s been put through the paces for just about every generation of PCI Express, and it’s worth refreshing now that the newest line of high-end GPUs has hit the market. The curiosity is this: Will a GPU be bottlenecked by PCI-e 3.0 x8, and how much impact does PCI-e 3.0 x16 have on performance?

We decided to test that question for internal research, but ended up putting together a small report for publication.

PCI Express Theoretical Max Bandwidth

The theoretical maximum bandwidth of PCI-e 3.0 is 8GT/s, or nearly 1GB/s per lane:

	PCI-e 1.0	PCI-e 2.x	PCI-e 3.0	PCI-e 4.x
x1	250MB/s	500MB/s	985MB/s	1969MB/s
x4	1000MB/s	2000MB/s	3940MB/s	7876MB/s
x8	2000MB/s	4000MB/s	7880MB/s	15752MB/s
x16	4000MB/s	8000MB/s	15760MB/s	31504MB/s

For our test, we’re looking at PCI-e Gen3 x8 vs. PCI-e Gen3 x16 performance. That means there’s a 66.7% difference in bandwidth available between the two, or a 100% increase from x8 to x16. But there’s a lot more to it than interface bandwidth: The device itself must exceed the saturation point of x8 (7880MB/s, before overhead is removed) in order to show any meaningful advantage in x16 (15760MB/s, before overhead is removed).

Use Cases, Future Tests, & Test Setup

The use cases here are not that large. Maybe you’ve got a thermal concern or a card that butts-up against the CPU cooler, or some sort of liquid routing challenge. HSIO lanes are assigned to ancillary devices – like PCIe SSDs – and won’t eat into the CPU lanes available to the GPU. We’re also not testing multiple GPUs, which is where we’d like to go next once we’ve got two of the same GTX 1080 in the lab. Ideally, we test in x16/x16, x16/x8, and x8/x8 – but that’s not possible right now. We’re also hoping to test dual-GPU, single-card configurations between an x8 and an x16 slot, as those may put more load on the interface.

For the time being, this test strictly looks at a single-GPU, single-card GTX 1080 Gaming X as it passes between x8 and x16 slots. If, for whatever reason, you’re debating the performance reduction from moving to an x8 PCI-e slot with a single card, that’s what this test looks into.

We used our normal test bench (detailed below) for this research. The EVGA X99 Classified motherboard is picky with its PCI-e slot utilization, and uses UEFI to clearly inform whether the connected device is receiving 1, 4, 8, or 16 lanes. We switched between the first x16 slot and the first x8 slot for these numbers, then validated in BIOS and software.

PCI-e generations can also be forced in the EVGA UEFI, but we did not explore the impact of PCI-e 2.x on the GTX 1080 at this time as it seemed even less likely of a use case.

Game Test Methodology

We tested using our GPU test bench, detailed in the table below. Our thanks to supporting hardware vendors for supplying some of the test components.

NVidia’s 368.39 drivers were used for game (FPS) testing. Game settings were manually controlled for the DUT. All games were run at presets defined in their respective charts. We disable brand-supported technologies in games, like The Witcher 3’s HairWorks and HBAO. All other game settings are defined in respective game benchmarks, which we publish separately from GPU reviews. Our test courses, in the event manual testing is executed, are also uploaded within that content. This allows others to replicate our results by studying our bench courses.

Windows 10-64 build 10586 was used for testing.

Each game was tested for 30 seconds in an identical scenario, then repeated multiple times for parity.

Average FPS, 1% low, and 0.1% low times are measured. We do not measure maximum or minimum FPS results as we consider these numbers to be pure outliers. Instead, we take an average of the lowest 1% of results (1% low) to show real-world, noticeable dips; we then take an average of the lowest 0. 1% of results for severe spikes.

GN Test Bench 2015	Name	Courtesy Of	Cost
Video Card	This is what we’re testing!	—	—
CPU	Intel i7-5930K CPU	iBUYPOWER	$580
Memory	Corsair Dominator 32GB 3200MHz	Corsair	$210
Motherboard	EVGA X99 Classified	GamersNexus	$365
Power Supply	NZXT 1200W HALE90 V2	NZXT	$300
SSD	HyperX Savage SSD	Kingston Tech.	$130
Case	Top Deck Tech Station	GamersNexus	$250
CPU Cooler	NZXT Kraken X41 CLC	NZXT	$110

For Dx12 and Vulkan API testing, we use built-in benchmark tools and rely upon log generation for our metrics. That data is reported at the engine level.

Video Cards Tested

MSI GTX 1080 Gaming X ($720)

PCI-e 3.0 x8 vs. x16 FPS Performance

Let’s just post all the charts first, then talk numbers – they’re similar enough that this is the easiest way to read the data.

Metro: Last Light

Shadow of Mordor

Call of Duty: Black Ops 3

GTA V

Ashes of Singularity (Dx12)

Here’s what we’ve got for performance:

Between AVG FPS metrics in Metro: Last Light, we’re seeing a 1.05% gap (1440p) and 0% gap (4K). Between 1% low metrics, that difference is 0.95% (1440p) and 0%.

For Shadow of Mordor, the numbers are similar – we’re seeing a 0.93% performance difference between AVG FPS metrics (or ~1% for 4K).

Black Ops 3, when there is a difference, shows one also just below 1%.

GTA V shows a difference of 0.52%. Ashes is similarly small.

Inconsequential Differences & Margins for Error

These numbers are close enough in some instances – like the GTA V 58. 3 vs. 58 FPS output – that they’re effectively within margin of test error and do not definitively show a performance gap. When a reasonable performance gap is shown – like the ~1% difference in Metro: Last Light numbers – it is imperceptible to the user but measurable with our tools. And we do mean imperceptible – we’re talking 96FPS vs. 95FPS, for Metro.

Metro, by the way, is the most reliable FPS benchmarking tool we have ever used. The game produces almost precisely the same AVG, 1% low, and 0.1% lows with every single test pass, and so we trust these metrics as being outside of test variance.

From a quick look, there is a little below a 1% performance difference in PCI-e 3.0 x16 and PCI-e 3.0 x8 slots. The difference is not even close to perceptible and should be ignored as inconsequential to users fretting over potential slot or lane limitations. We are not sure how this scales with SLI (particularly MDA ‘mode’) or dual-GPU cards, but hope to research once we’ve got more hardware in the lab.

We are also currently investigating the impact of PCI-e lanes on lower capacity VRAM cards, like 4GB. Hits to system resources may stress the interface more.

Editorial: Steve “Lelldorianx” Burke
Video: Andrew “ColossalCake” Coleman

PCI Express — differences between x1, x4, x8, x16

Author Roman Kolotravov To read 7 min Views 10.1k. Posted by June 12, 2018

What’s interesting in this article:

What is a PCI Express bus?
The impact of the number of lanes on throughput
Types of devices using PCI Express x2, x4, x8, x12, x16 and x32
PCI-E port and lane sizes can vary

The PCI Express standard is one of the foundations of modern computers . PCI Express slots have long taken a firm place on any desktop computer motherboard, supplanting other standards such as PCI. But even the PCI Express standard has its own varieties and connection patterns that differ from each other. On new motherboards, starting around 2010, you can see a whole scattering of ports on one motherboard, labeled as PCIE or PCI-E , which may differ in the number of lines: one x1 or several x2, x4, x8, x12, x16 and x32.

So, let’s find out why there is such confusion among the seemingly simple PCI Express peripheral port. And what is the purpose of each PCI Express x2, x4, x8, x12, x16 and x32 standard?

What is a PCI Express bus?

Back in the 2000s, when the aging PCI (ext. — Peripheral Component Interconnection) standard moved to PCI Express, the latter had one huge advantage: instead of the serial bus, which was PCI, a point-to-point access bus was used. This meant that each individual PCI port and the cards installed in it could take full advantage of the maximum bandwidth without interfering with each other, as they did when connected to the PCI . In those days, the number of peripherals inserted into expansion cards was plentiful. Network cards, audio cards, TV tuners and so on — all required a sufficient amount of PC resources. But unlike the PCI standard, which used a common bus for data transfer with several devices connected in parallel, PCI Express, if considered in general, is a packet network with a star topology.

PCI Express x16, PCI Express x1 and PCI on the same board

In layman’s terms, imagine your desktop PC as a small shop with one or two vendors. The old PCI standard was like a grocery store: everyone was waiting in line to be served, having problems with the speed of service, limited to one seller behind the counter. PCI-E is more like a hypermarket: each customer moves for groceries along their own individual route, and several cashiers take orders at the checkout at once.

It is obvious that the hypermarket outperforms a regular store in terms of service speed by several times, due to the fact that the store cannot afford the throughput of more than one seller with one checkout.

Also with dedicated data lanes for each add-on card or integrated motherboard components.

Not about PCI, but also interesting:

👉 Why is it important to set a BIOS password, and how to do it?

👉 Dealt with all kinds of computer ports/interfaces and their adapters

The impact of the number of lines on throughput

Now, to expand our metaphor with a store and a hypermarket, imagine that each department of the hypermarket has its own cashiers reserved only for them . This is where the idea of multiple data lanes comes in.

The

PCI-E has gone through many changes since its inception. Currently, new motherboards usually use version 3 of the standard, with the faster version 4 becoming more common, with version 5 expected in 2019.year. But different versions use the same physical connections, and these connections can be made in four basic sizes: x1, x4, x8 and x16. (x32 ports exist, but are extremely rare on regular computer motherboards).

The different physical sizes of the PCI-Express ports make it possible to clearly distinguish them by the number of simultaneous connections to the motherboard: the larger the port physically, the more maximum connections it can transfer to or from the card. These compounds are also called lines . One line can be thought of as a track consisting of two signal pairs: one for sending data and the other for receiving.

Different versions of the PCI-E standard allow different speeds on each lane. But generally speaking, the more lanes there are on a single PCI-E port, the faster data can flow between the peripheral and the rest of the computer.

Returning to our metaphor: if we are talking about one seller in the store, then the x1 lane will be this only seller serving one client. A store with 4 cashiers already has 4 lines x4 . And so on, you can list cashiers by the number of lines, multiplying by 2.

Various PCI Express cards

Types of devices using PCI Express x2, x4, x8, x12, x16 and x32

For PCI Express 3. 0 version, the total maximum data transfer rate is 8 Gb / s. In reality, the speed for the PCI-E 3 version is slightly less than one gigabyte per second per lane.

Thus, a device that uses a PCI-E x1 port, such as a low-power sound card or Wi-Fi antenna, will be able to transfer data at a maximum speed of 1 Gbps.

A card that physically fits into a larger slot — x4 or x8 , such as a USB 3.0 expansion card, will be able to transfer data four or eight times faster, respectively.

PCI-E x16 ports are theoretically limited to a maximum bandwidth of about 15 Gb/s. This is more than enough in 2017 for all modern graphics cards developed by NVIDIA and AMD.

Most modern graphics cards use PCI Express

The PCI Express 4.0 protocol already allows 16 GT/s, while PCI Express 5.0 will use 32 GT/s.

But there are currently no components that can use this amount of bandwidth at maximum bandwidth. Modern high-end graphics cards typically use the x16 PCI Express 3. 0 standard. It makes no sense to use the same bandwidths for a network card that will use only one line on an x16 port, since the Ethernet port is only capable of transmitting data up to one gigabit per second (which is about one eighth of the bandwidth of one PCI-E lane — remember: eight bits in one byte).

There are PCI-E SSDs on the market that support the x4 port, but they look like they will soon be superseded by the rapidly evolving new M.2 standard. for SSDs that can also use the PCI-E bus. High-end network cards and enthusiast hardware such as RAID controllers use a mix of x4 and x8 formats.

PCI-E port and lane sizes can vary.

This is one of the more confusing PCI-E challenges: a port can be x16 sized, but not have enough lanes to pass data, for example, just x4. This is because even though PCI-E can carry an unlimited number of individual connections, there is still a practical limit to the bandwidth of the chipset. Cheaper motherboards with more budget chipsets may only have one x8 slot, even though that slot can physically accommodate an x16 form factor card.

In addition, gamer-focused motherboards include up to four full x16 PCI-E slots and as many lanes for maximum throughput.

For example — ASUS X99-DELUXE II RTL. Motherboard with 4 PCI-E with x16

Obviously, this can cause problems. If the motherboard has two x16 slots, but one of them has only x4 stripes, then adding a new graphics card will reduce the performance of the first one by as much as 75%. This, of course, is only a theoretical result. The architecture of the motherboards is such that you will not see a sharp drop in performance.

A proper configuration of two graphics cards must use exactly two x16 slots if you want maximum comfort from a tandem of two video cards. The manual at the office will help you find out how many lines on your motherboard this or that slot has. manufacturer’s website.

Sometimes manufacturers even mark the number of lines on the motherboard textolite next to the slot:

Labels on the motherboard PCI Express x1 and x4

You need to know that a shorter x1 or x4 card can physically fit into a longer x8 or x16 slot. The contact configuration of the electrical contacts makes this possible. Naturally, if the card is physically larger than the slot, then it will not work to insert it.

So remember, when buying expansion cards or upgrading current ones, you must always remember both the size of the PCI Express slot and the number of required lanes.

PCI-Express v2.0 x16 vs. x8. 2011 version

Introduction
Test configuration
Instrumentation and Test Method
Test results: performance comparison

Arcania — Gothic 4 (Fishir)
Assassin’s Creed Brotherhood (Central Rome)
Battlefield Bad Company 2 (Building Forces)
Bulletstorm (Last train to town)
Call of Duty: Black Ops (Marines)
Colin McRae DIRT 2 (Benchmark — Battle of Battersea London)
Crysis (Benchmark — Harbor)
Crysis 2 (Benchmark — Downtown)
Dirt 3 (Benchmark — ASPEN)
Dragon Age 2 (Ragged Shore)
Formula 1 2010 (Benchmark)
Just Cause 2 (Benchmark — Concrete jungle)
Lost Planet 2 (Benchmark B)
Mafia 2 (Chapter 15 — Through Adversity to the Stars)
Medal of Honor 2010 (Day 2 — Neptune Nets)
Metro 2033 (Benchmark)
Need for Speed: Shift 2 Unleashed (Monza Italy)
Shogun 2 Total War (Battle of Okehadzama)
StarCraft 2 (Bets are placed)
Test Drive Unlimited 2 (Super Championship: Kaneohe Bay)

Terminals

Time does not stand still, since the last review on this topic («PCI-Express v2. 0 x16 + x16 interface vs. PCI-Express v2.0 x8 + x8″), the lines of video cards from both manufacturers — NVIDIA and AMD — have been updated.

recommendations

This article will discuss the impact of the throughput of PCI-Express x8 and PCI-Express x16 slots on the performance of single GPUs and graphics duos (using the example of GeForce GTX 570 1280 MB and Radeon HD 6970 2048 MB) in gaming applications .

Tested on the following bench:

Processor: Intel Core i7 920 (Bloomfield, D0, L3 8 MB), 1.18 V, Turbo Boost — on, Hyper Threading — off — 2660 @ 4300 MHz (1.35 V)
Motherboard: GigaByte GA-EX58-UD5, BIOS F5
CPU cooling system: Cooler Master V8 (~1100 rpm)
RAM: 3 x 2048MB DDR3 Corsair TR3X6G1600C7 (Spec: 1528MHz / 7-7-7-18-1t / 1.65V) , X.M.P. — off
Drive subsystem: SATA-II 500 GB, WD 5000KS, 7200 rpm, 16 MB
PSU: Thermaltake Toughpower 1200 Watts (stock fan: 140mm blown)
Housing: open test bench
Monitor: 30″ DELL 3008WFP (Wide LCD, 2560×1600 / 60Hz)

Video cards:

2 x GeForce GTX 570 1280 MB — 732/732/3800 MHz (Zotac)
2 x Radeon HD 6970 2048 MB — 880/880/5500 MHz (GigaByte)

Software:

Operating system: Windows 7 x64 SP1
Video card drivers: GeForce 275. 27 WHQL and Catalyst 11.5 WHQL Hotfix

For a more visual comparison of video cards, all games used as test applications were launched at 1280×1024, 1920×1080 and 2560×1600 resolutions.

Built-in benchmarks, utilities FRAPS v3.2.1 build 11425 and AutoHotkey v1.0.48.05 were used as performance measurement tools. List of game applications:

Arcania — Gothic 4 (Fishir)
Assassin’s Creed Brotherhood (Central Rome)
Battlefield Bad Company 2 (Building Forces)
Bulletstorm (Last train to town)
Call of Duty: Black Ops (Marines)
Colin McRae DIRT 2 (Benchmark — Battle of Battersea London)
Crysis (Benchmark — Harbor)
Crysis 2 (Benchmark — Downtown)
Dirt 3 (Benchmark — ASPEN)
Dragon Age 2 (Ragged Shore)
Formula 1 2010 (Benchmark)
Just Cause 2 (Benchmark — Concrete Jungle)
Lost Planet 2 (Benchmark B)
Mafia 2 (Chapter 15 — Through Adversity to the Stars)
Medal of Honor 2010 (Day 2 — Neptune Nets)
Metro 2033 (Benchmark)
Need for Speed: Shift 2 Unleashed (Monza Italy)
Shogun 2 Total War (Battle of Okehadzama)
StarCraft 2 (Bets are placed)
Test Drive Unlimited 2 (Super Championship: Kaneohe Bay)

In all games, minimum and average FPS values were measured.

In tests where it was not possible to measure the minimum FPS , this value was measured by the FRAPS utility.

VSync was disabled during tests.

To avoid errors and minimize measurement errors, all tests were performed three to five times. When calculating the average FPS, the final result was taken as the arithmetic mean of the results of all runs (three not «idle»). As the minimum FPS, the minimum value of the indicator based on the results of three runs was chosen.

Specifications for NVIDIA and AMD graphics cards

Let’s go directly to the tests.

Version 1.1.0
DirectX9

texture quality — high
SSAO quality — high
light quality — high
shadow quality — ultra
dynamic shadows — world and geometry
shadows — world and geometry
the quality of the characters is high
world quality — high
particle quality — high
exposure — incl.
glare — incl.
face detail — incl.
post-processing — incl.

1280×1024

Please enable JavaScript to see graphs

1920×1080

Please enable JavaScript to see graphs

2560×1600

Please enable JavaScript to see graphs

Minimum and average FPS

Reinstalling GeForce GTX 570, CrossFireX 2 x Radeon HD 6970 and Radeon HD 6970 from PCI-Express v2.0 x16 slots to PCI-Express v2.0 x8 reduced performance by a slight 2% — 5% while SLI results 2 x GeForce GTX 570 are down a more noticeable 9% — 12% depending on resolution.

Version 1.04
DirectX9

Full Screen Anti-Aliasing (MSAA) 4
environmental quality — 6
texture quality — 3
shadow quality — 5
reflection quality — high
character quality — 5
post-effects — incl.

1280×1024

Please enable JavaScript to see graphs

1920×1080

Please enable JavaScript to see graphs

2560×1600

Please enable JavaScript to see graphs

Minimum and average FPS

Reducing the bandwidth of the PCI-Express interface in the adventure game Assassin’s Creed Brotherhood had almost no effect on the results of NVIDIA video cards and reduced the performance of a single and two Radeon HD 6970 at 5% — 9% depending on resolution.

Version 602574
DirectX 11

full screen anti-aliasing (AA) 4
anisotropic filtering (AF) 16
level of detail — high
texture quality — high
shadow quality — high
effects quality — high
complex HBAO shading — incl.

1280×1024

Please enable JavaScript to see graphs

1920×1080

Please enable JavaScript to see graphs

2560×1600

Please enable JavaScript to see graphs

Minimum and average FPS

In the shooter Battlefield Bad Company 2, reducing the bandwidth of the PCI-Express interface reduced the performance of two GeForce GTX 570 by 2% — 3% and a single NVIDIA video card by 4% — 6%. AMD graphics accelerator results decreased by 5% — 12%, with a single Radeon HD 6970 «sank» by a larger amount than the duet.