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Your PC probably has a slot that looks like this.

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It's a PCI Express X16 slot, and it's commonly used for graphics cards,

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as it's one of the fastest connections on your motherboard. Even the chonkiest, most powerful GPUs can be handled

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by a single one of these slots, no problem. But there is another.

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Did you know that PCI Express X32

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is a real thing that actually exists? What the heck would you do with a slot that's twice as long?

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Well, to be clear, it's very difficult to find slots physically bigger

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than that standard X16 size. Remember that those numbers,

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when we're talking about PCI Express, refer to the number of lanes,

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not necessarily the physical size of the slot. A tiny M.2 SSD often uses four PCI Express lanes,

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even though the connector is quite a bit smaller than a regular PCIe X4 sized slot.

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How exactly does PCI Express X32 work then?

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But it turns out that the PCI Express standard doesn't support a single link greater than X16.

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The reason for this is because it's very difficult to actually implement links this wide in hardware.

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You see, when you send data down a PCI Express link,

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say to a graphics card, that data is striped across multiple lanes,

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and doing this is not trivial. When the data arrives wherever it's going,

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it has to be deskewed, meaning synchronized.

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Although PCI Express is a serial interface that doesn't require the data on each lane

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to arrive at exactly the same time, synchronizing the data still involves hardware overhead.

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And once you start getting past 16 lanes, it's just too much to keep up with.

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So instead of having one big slot, these higher PCI Express connections

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use a trick called driver binding. Essentially, this allows multiple PCIe devices

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to talk to each other and coordinate their traffic

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so they can act as one big device. So a PCIe X32 link is actually two X16 links

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mashed together in software, with the devices installed in two normal X16 slots.

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The performance overhead involved with driver binding for X32 isn't too bad.

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But if you were to theoretically go up to say X64,

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you'd likely need more hardware, as at that point you just have too many transactions

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for your poor system to handle. But wait a sec, why the heck would you need

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that much bandwidth to begin with? Now the appeal of having this many PCI Express lanes

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isn't so you can do something like squeeze more performance

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out of your graphics card. Even an RTX 4090 barely improves going from eight lanes

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to 16 lanes on a PCIe 4.0 slot.

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Instead, driver binding is used in applications where all the bandwidth you can get is appealing.

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You often see X32 links in certain kinds of networking cards,

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mostly for server and data center use. Although NVIDIA is obviously known more for GPUs and AI,

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they make a line of network adapters that supports both Ethernet

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and another high speed networking protocol called Infiniband.

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This product, for example, goes into a standard PCIe Express X16 slot,

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but it comes with a second auxiliary card with the same connector.

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They work in tandem to provide an X32 connection for extra bandwidth in case you're using

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a previous revision of PCIe Express that doesn't provide enough bandwidth

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to take full advantage of the network adapter's speed. There's also a special cable connecting them

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to allow them to share data while taking some of the pressure off of the PCIe Express bus itself.

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And connecting multiple machines with crazy amounts of bandwidth isn't even a rare use case.

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With how much growth we've seen with data hungry cloud services

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for applications like AI, gaming, and ultra high def video,

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data centers are already moving towards 400 gigabit connections or even beyond.

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That's 400 times faster than what you'll find

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in most garden variety desktop PCs, which is also part of why you simply don't need

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PCIe Express X32 in your personal rig.

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Although I'm sure some of you are already thinking of ways you're gonna justify your purchase.

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Hey, thanks for watching this video. Like it if you liked it. Dislike it if you disliked it.

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Check out our other video on PCIe Express 6.0.

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Comment below with video suggestions and don't forget to subscribe and follow to TechWiki,

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