The Raspberry Pi 4 is the most powerful Raspberry Pi computer to date, and the first to support up to 4GB of RAM. It’s also the first to support USB 3.0 — and the chip that controls USB is connected to a PCI Express interface.

But that doesn’t mean you can attach peripherals directly to the PCIe interface… or does it?

Tomasz Mloduchowski wanted to see if it was possible to expose the interface, and it turns out that it is… although I’m not sure how useful this hack would be for most users.

The hack involved desoldering a VIA VL805 chip from the motherboard to expose the bus, attaching a PCIe riser, and connecting a compatible controller.

When all is said and done, it’s possible to connect peripherals directly to the PCIe bus.

That said, in most case you’re probably going to be better off just plugging hardware into the USB 3.0 ports. You can easily connect a USB hard drive or SSD that way if you want more storage (or faster storage) than you would get from a microSD card. And exposing the PCIe interface only gives you a single lane — which isn’t enough to hook up something like a graphics card.

Still, it’s impressive to see that it can be done.

https://www.youtube.com/watch?v=_4YRZRCE5z4

via Hackster.io and Tom’s Hardware

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10 replies on “Hacker makes the Raspberry Pi 4’s PCIe interface usable (sort of)”

  1. Can’t wait for some to do this and try to connect an RTX 2080 Ti GPU to this

      1. No doubt someone will do it eventually just to see if Crysis will run on it or not as well as the usual round of tests lol

        1. How is an ARM system supposed to run an x86-Program?
          Crysis is too demanding to run through Windows 10S emulation, and hasn’t been ported either.

          The most demanding Windows-ARM games I could find are Unknown City, Overkill 3, Modern Combat 4, GTA San Andreas, Asphalt 8 and Minecraft. So yeah, I’m not sure how a RTX 2080 Ti is supposed to drive those 3D Games, since they can easily be run on something like a QSD 600 device.

          1. I’m assuming whoever attempts it would try using Windows 10 on ARM’s built in x86 emulation. But that’s not really point. There’s a lot of youtubers out there that do these kinds of experiments for a living. Someone will try it out eventually, whether it works or not. One Youtuber out there, forgot his name, likes to pair RTX 2080 Ti’s with the weakest CPU’s possible like Intel Atoms or early 2000’s Pentiums/Celerons just to see how top of the line modern games perform.

      2. Not worth it IMO. I doubt the CPU on a Raspberry Pi (any model) has enough processing power to make a mainline graphics card of much use. Unless you edit video professionally, play heavy AAA game titles or do CAD I can’t think of many uses where a dedicated graphics card is necessary nowadays, anyway.

  2. Pic, and it (probably) didn’t happen. I believe this to be a fake.

    1. The picture looks legit… a good place to grap the Tx and Rx lanes are on the USB3 connector (blue cable). The out-of-band communication lines do not appear to be bridged over (maybe it defaults to Gen1 speed?). I am assuming that the common ground is also on the blue cable.
      It might be fake, but I can’t see an obvious reason from the picture.

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