Why usb-c intead of pci-e?

I mean, wouldn’t it be simpler to have just pci-e on the motherboard and the expansion cards and the expansion to use a more standard connector(pci-e) with no in-between translations.
Just make some sort of pci-e x1 or x2 and make a power connector on the side, and make it an expansion standard, so if something needs more power than the pci has, it can take it from the power connector.

Also doesn’t the actual configuration creates some overhead in some cases?. I don’t know but I imagine the motherboard translating to usb and after that to wherever expansion you are putting in.

I was also thinking in the afterlife of the motherboard, if the it has 4 more pci-e slots (instead of usb), it will be so useful, wanna make a crazy nas, just add a lot of sata cards, want more lan, throw it in, need more usb for your desktop, no problem.

I make a post in the ltt forum a while ago, can i put the link here so I don’t have to duplicate it?

So you’d need a usb controller on the module if you wanted usb? Or hell a freaking gpu if you want displayport?

The whole point of usb-c ist that it can by design carry all kinds of stuff, it can do power (pd), usb (obviously), displayport (and from there hdmi via a passive converter) and all of that IO can come directly of the soc.

What you are describing sounds more like a desktop mainboard.

Anyway, the cheaply accessible pcie is in the nvme slot and the wifi slot that gives you 4+1 lane. Getting the other 8 from the thunderbolt ports is a lot more expensive and bulky.

So just slaping an hba (gives you as many sata ports as you want) into the m.2 slot and run a 2.5 gbit usb network card is probably your cheapest option. Though just using a desktop or server mainboard is going to be a lot less painful, especially since you’ll need a psu for the drives anyway.


I didn’t thought about the display, but good point, that could be cheaper

I am thinking about the penalty you get from connecting to a usb in comparison to pci-e and all the devices that can connect natively to it

But if the usb chip is on the motherboard, moving it to the expansion card is not unthinkable, if I think about all the things that can be attached to pci, and if I have a usb chip on the card, I don’t need a gpu for adding a display port.

The expansion cards should also have more things on, the space is there. In the past were more ports available on a laptop, they were slowly taken out to connect a usb hub/dock for things that were built in

And if the cpu has embedded usb/thunderbolt, put it embed it on the laptop, I can’t already use it as anything else without adapting/translating it

I am just curious, is not unthinkable, is not impossible, they have done a bigger brother of that for the gpu, and have more expansion options because is pci-e, there will be also more use cases for the afterlife.

Talking about desktops and laptops, I feel that the atx desktop pcs are daying, the laptops and nucs are getting so powerful now that it doesn’t make sense anymore having a gigantic box eating so much energy, so if pcs are going small and share the hardware, and framework suggests that my laptop is gonna have a second life as my desktop or server, it will be nice to have available more pci-e

The idea of having an expansion card that converted the USB port to PCIe was mentioned here before, and others brought up the fact that USB is rated for more plug/unplugs before wearing out. PCIe being an internal connector means that it isn’t designed for you to be swapping out the things attached to it all the time, so USB-C allows you to change expansion cards more often than PCIe.

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I’m not sure there is more stuff you can connect natively via pcie than usb (there is a lot of both) but most importantly they are not the same stuff.

Pretty much everything is completely or mostly on the cpu. Plus stuff like usb-pd is something shared across all prots, that would get really compicated if it was multiple different controllers.

Have you seen the development for the expansion cards, especially stuff like the usb-a+usb-c one? You may be massively overestimating how much space is in those things, fitting even a full blown pcie usb controller in one of those could be quite challenging not to mention all the other drawbacks like the power consumption, cost and complexity.

If you look at semi modern laptop schematics you’ll find the built in usb ports are already quite utilized (webcam, touch, touchpad, fingerprint reader …), manufacturers sometimes even go off spec a little if the run out like lenovo using the 3.0 and 2.0 section of a single port for different things on some models. If you do not use certain things there are connectors on the board that carry usb you can use. Framework has published a pinout for most connectors on their github. While I would prefere having the schematic that is pretty good too. Thunderbolt is also mostly on the cpu.

It is not unthinkable but while it would make a pretty neat sbc it would make for a pretty terrible laptop, USB-C is pretty much made for this, it can hotplug (which pcie only kinda can and only with speciffic hardware and software support) and carry a wide variety of things, especially things you’d actually use on a laptop. Putting separate controllers on each port would definitely have it’s pros but it would send cost and complexity through the roof. Then there is that tiny little issue of power consumption, for a nas noone cares about a watt or 2 extra of idle power but putting controllers on each port would absolutely murder battery life even with the most gracefully sleeping pcie usb controllers and whatnot.

The gpu module there is a bit of a speical case and you’ll notice the 16 inch still has usb for the regular stuff.

Mobile stuff is indeed getting more and more powerfull but desktop stuff is getting even more powerfuller XD. Stuff making sense or not sense is a bit of a individual case. I can very much belive that it does not make sense for you.

Anyway, if you slap an hba in the m.2 slot and get a solid usb nic the current board allready makes a pretty sweet nas, especially if yoou don’t want to go 10gig.

And if you want a board with lots of little pcie slots, you can get those mining board with tons of pcie 1x slots really cheap right now.

While I personally would like to have access to more pcie on the board the connectors being usb-c makes a lot more sense for a laptop.

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Adrian_Joachim: you are right, the p&p thing is not a thing with pci-e, that is a problem and to make it p&p will be more engineering work, and looking from the laptop side, usb is the best option, what I mentioned goes more to the second life or diy what is not the main point

It’s not a thing by default, it is a thing though but it is a pain in both software and hardware. In the server space it’s more of a thing, though these days a server is more likely to be replaced than having parts replaced while it’s running. Helle there even was hotplug ram at some point, imagine that.

Second life as a mid tier nas is still very much on the table though, putting a hba on the nvme slot would give you enough bandwidth (~4gb/s for a 3.0 one or ~2gb/s for a 2.0) to saturate a 2.5 or 5gbit usb network card (or hell one of those thunderbolt 10gbit ones) which is probably enough for most people:

  • 10-20$ for m.2 to pcie adabter
  • 50-100$ for an hba with 8 ports (if you need more than 8 you can use sas expanders)
  • 20$ for a 2.5Gbit usb-c network card
  • ?$ for a case
  • ?$ for an atx power supply

Also if you just need more pcie slots but not necessarily the bandwidth, you can get some of those cheap 1x to multiple 1x pcie splitters that were used for mining, bandwidth sucks but you can put a lot of devices on there.

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