pci-e 1x和4x_为什么主板上的PCI Express端口大小不同？ x16，x8，x4和x1说明

pci-e 1x和4x

The PCI Express standard is one of the staples of modern computing, with a slot on more or less every desktop computer made in the last decade. But the nature of the connection is somewhat nebulous: on a new PC, you might see a half-dozen ports in three or four different sizes, all labelled “PCIE” or PCI-E.” So why the confusion, and which ones can you actually use?

PCI Express标准是现代计算的主要组成部分之一，在过去的十年中，每台台式计算机上都或多或少地装有插槽。但是连接的本质有些模糊：在新的PC上，您可能会看到六个或六个，三个或四个不同大小的端口，都标记为“ PCIE”或PCI-E。那么，为什么要混淆？您可以实际使用哪些？

了解PCI Express总线 (Understanding the PCI Express Bus)

As an upgrade to the original PCI (Peripheral Component Interconnect) system, PCI Express had one huge advantage when it was initially developed in the early 2000s: it used a point-to-point access bus instead of a serial bus. That meant that each individual PCI port and its installed cards could take full advantage of their maximum speed, without multiple cards or expansions being clogged up in a single bus.

作为对原始PCI(外围组件互连)系统的升级，PCI Express在2000年代初期最初开发时具有一个巨大的优势：它使用点对点访问总线而不是串行总线。这意味着每个单独的PCI端口及其安装的卡都可以充分利用其最大速度，而不会在单个总线中阻塞多个卡或扩展。

In layman’s terms, imagine your desktop PC as a restaurant. The old PCI standard was like a deli, everyone waiting in a single line to get served, with the speed of service limited by a single person at the counter. PCI-E is more like a bar, every patron sitting down in an assigned seat, with multiple bartenders taking everyone’s order at once. (Okay, so it’s never possible to get a bartender to every patron right away, but let’s pretend this is a really great bar.) With dedicated data lanes for each expansion card or peripheral, the entire computer can access components and accessories faster.

用外行的话来说，将台式PC想象成一家餐馆。旧的PCI标准就像是熟食店，每个人都在一行中等待服务，而服务速度受到柜台上一个人的限制。 PCI-E更像是一个酒吧，每个顾客都坐在一个指定的座位上，有多个调酒师一次接管每个人的订单。 (好吧，因此永远不可能马上让每个顾客都来调酒师，但是我们假装这是一个非常棒的酒吧。)借助每个扩展卡或外围设备的专用数据通道，整个计算机可以更快地访问组件。

Now to extend our deli/bar metaphor, imagine that some of those seats have multiple bartenders reserved just for them. That’s where the idea of multiple lanes comes in.

现在扩展我们的熟食店/酒吧的隐喻，想象一下那些座位中有一些只为他们保留的调酒师。这就是多车道的想法出现的地方。

快车道中的生活 (Life in the Fast Lanes)

PCI-E has gone through multiple revisions since its inception; currently new motherboards generally use version 3 of the standard, with the faster version 4 becoming more and more common and version 5 expected to hit in 2019. But the different revisions all use the same physical connections, and those connections can come in four primary sizes: x1, x4, x8, and x16. (x32 ports exist, but are extremely rare and generally not seen on consumer hardware.)

自成立以来，PCI-E经历了多次修订。当前，新主板通常使用该标准的版本3，更快的版本4变得越来越普遍，而版本5有望在2019年推出。但是不同的版本都使用相同的物理连接，并且这些连接可以有四种主要尺寸：x1，x4，x8和x16。 (存在x32端口，但极为罕见，通常在消费类硬件上看不到。)

The different physical sizes allow for different numbers of simultaneous data pin connections to the motherboard: the larger the port, the more maximum connections on the card and the port. These connections are colloquially known as “lanes,” with each PCI-E lane comprised of two signaling pairs, one for sending data and the other for receiving data. Different revisions of the PCI-E standard allow for different speeds on each lane. But generally speaking, the more lanes there are on a single PCI-E port and its connected card, the faster data can flow between the peripheral and the rest of the computer system.

不同的物理尺寸允许同时将不同数量的数据引脚连接到母板：端口越大，卡和端口上的最大连接数越多。这些连接俗称“通道”，每个PCI-E通道由两对信令组成，一对用于发送数据，另一对用于接收数据。 PCI-E标准的不同修订版允许每个通道的速度不同。但是通常来说，单个PCI-E端口及其连接的卡上的通道越多，外围设备与计算机系统其余部分之间的数据传输速度就越快。

Going back to our bar metaphor: if you imagine each patron sitting at the bar as a PCI-E device, then an x1 lane would be a single bartender serving a single customer. But a patron sitting in the assigned “x4” seat would have four bartenders fetching him drinks and food, and the “x8” seat would have eight bartenders just for her drinks, and the one in the “x16” seat would have a whopping sixteen bartenders just for him. And now we’re going to stop talking about bars and bartenders, because our poor metaphorical drinkers are in danger of alcohol poisoning.

回到我们的酒吧隐喻：如果您想象每个顾客都是作为PCI-E设备坐在酒吧里的，那么x1车道就是一个为单个客户服务的调酒师。但是坐在分配的“ x4”座位上的顾客将有四名调酒师为他获取饮料和食物，而“ x8”座位的座位上将有八名调酒师专门为她喝酒，而在“ x16”座位的座位上将有多达十六名调酒师。调酒师只为他。现在，我们将不再谈论酒吧和调酒师，因为我们这些隐喻性较差的饮酒者有酒精中毒的危险。

哪些外设使用哪些端口？ (What Peripherals Use Which Ports?)

For the common revision 3.0 version of PCI Express, the maximum per-lane data rate is eight gigatransfers, a term that means “all the data and electronic overhead at once.” In the real world, the speed for PCI-E revision 3 is a little less than one gigabyte per second, per lane.

对于PCI Express的通用修订版3.0版，最大每通道数据传输速率为8 gigatransfers，这个术语意味着“一次所有数据和电子开销”。在现实世界中，PCI-E修订版3的速度为每通道每秒小于1 GB。

相关： 现在是购买新的NVIDIA或AMD显卡的好时机吗？

So a device that uses a PCI-E x1 port, like a low-power sound card or a Wi-Fi antenna, can transfer data to the rest of the computer at approximately 1GBps. A card that bumps up to the physically larger x4 or x8 slot, like a USB 3.0 expansion card, can transfer data four or eight times faster—and it would need to, if more than two of those USB ports were being used at their maximum transfer rate. The PCI-E x16 ports, with a theoretical maximum of around 15GBps on the 3.0 revision, are used for almost all modern graphics cards designed by NVIDIA and AMD.

因此，使用PCI-E x1端口的设备(例如低功耗声卡或Wi-Fi天线)可以大约1GBps的速率将数据传输到计算机的其余部分。可以扩展到物理上更大的x4或x8插槽的卡(例如USB 3.0扩展卡)可以将数据传输速度提高四倍或八倍-如果要最大使用两个以上的USB端口，则需要这样做。传输速率。 PCI-E x16端口在3.0版本上理论上最大约为15GBps，几乎用于NVIDIA和AMD设计的所有现代图形卡。

相关： 什么是M.2扩展插槽，如何使用？

There aren’t any set guidelines for which expansion cards will use which number of lanes. Graphics cards tend to use x16 just for the sake of maximum data transfer, but obviously you don’t need a network card to use an x16 port and sixteen full lanes when its Ethernet port is only capable of transferring data at one gigabit per second (about an eighth of the throughput of one PCI-E lane—remember, eight bits to a byte). There are a small amount of PCI-E mounted solid state drives that prefer an x4 port, but those seem to have been swiftly overtaken by the new M.2 standard, which can also use the PCI-E bus. High-end network cards and enthusiast equipment like adapters and RAID controllers use a mix of x4 and x8 formats.

对于哪个扩展卡将使用多少个通道，没有任何设定的准则。图形卡倾向于使用x16只是为了最大程度地传输数据，但是很明显，当其以太网端口只能以每秒1吉比特的速度传输数据时，不需要网卡使用x16端口和16条全通道。大约是一个PCI-E通道吞吐量的八分之一(请记住，八位到一个字节)。有少量的PCI-E固态驱动器更喜欢x4端口，但似乎已被新的M.2标准Swift取代，后者也可以使用PCI-E总线。高端网卡和发烧级设备(如适配器和RAID控制器)使用x4和x8格式的混合。

切记：PCI-E端口大小和通道可能不一样 (Remember: PCI-E Port Size and Lanes May Not Be the Same Thing)

相关文章： 什么是“芯片组”，为什么我应该关心？

Here’s one of the more confusing parts of the PCI-E setup: a port might be the size of an x16 card, but only have enough data lanes for something much less speedy, like x4. This is because while PCI-E can accommodate basically unlimited amounts of individual connections, there’s still a practical limit on the lane throughput of the chipset. Cheaper motherboards with more budget-oriented chipsets might only go up to a single x8 slot, even if that slot can physically accommodate an x16 card. Meanwhile, “gamer” motherboards will include up to four full x16-size and x16-lane PCI-E slots for maximum GPU compatibility. (We’ve discuss this in more detail here.)

这是PCI-E设置中比较混乱的部分之一：端口可能只有x16卡的大小，但只有足够的数据通道来传输速度较慢的数据，例如x4。这是因为尽管PCI-E可以容纳不限数量的单个连接，但是芯片组的通道吞吐量仍然存在实际限制。具有更多预算型芯片组的较便宜主板可能只能使用一个x8插槽，即使该插槽实际上可以容纳x16卡也是如此。同时，“游戏”主板将包括多达四个完整的x16尺寸和x16通道PCI-E插槽，以实现最大的GPU兼容性。 (我们在这里对此进行了更详细的讨论。)

Obviously, this can cause problems. If your motherboard has two x16-sized slots, but one of them has only x4 lanes, then plugging your fancy new graphics card into the wrong slot could bottleneck its performance by 75%. That’s a theoretical result, of course: the architecture of motherboards means you won’t see such a dramatic decline. The point is, the right card needs to go in the right slot.

显然，这可能会引起问题。如果您的主板有两个x16大小的插槽，但其中一个只有x4通道，那么将新奇的图形卡插入错误的插槽可能会使性能降低75％。当然，这是理论上的结果：主板的体系结构意味着您不会看到如此急剧的下降。关键是，正确的卡需要插入正确的插槽。

Luckily, the lane capacity of the specific PCI-slots is generally spelled out in the computer or motherboard manual, with an illustration of which slot has which capacity. If you don’t have your manual, the number of lanes is generally written on the PCB of the motherboard next to the port, like so:

幸运的是，通常在计算机或主板手册中阐明了特定PCI插槽的通道容量，并说明了哪个插槽具有哪个容量。如果您没有手册，则通常将通道数写在主板上端口旁边的PCB上，如下所示：

Also, a shorter x1 or x4 card can physically fit into a longer x8 or x16 slot: the initial pin configuration of the electrical contacts makes it compatible. The card may be a bit loose physically, but when screwed into place in the expansion slots of a PC case, it’s more than adequately sturdy. Naturally, if a card’s contacts are physically larger than the slot, it can’t be inserted.

同样，较短的x1或x4卡可以物理地插入较长的x8或x16插槽中：电触点的初始引脚配置使其兼容。该卡在物理上可能有点松动，但是在将其拧入PC机壳的扩展插槽中时，它的坚固程度远远超过其坚固性。自然，如果卡的触点物理上大于插槽，则无法插入。

So remember, when buying expansion or upgrade cards for PCI Express slots, you need to be mindful of both the size and the lane rating of your available ports.

因此请记住，在购买用于PCI Express插槽的扩展卡或升级卡时，需要注意可用端口的大小和通道额定值。

Image credit: Newegg, Amazon

图片来源： Newegg ，亚马逊

翻译自: https://www.howtogeek.com/322189/why-are-the-pci-express-ports-on-my-motherboard-different-sizes-x16-x8-x4-and-x1-explained/