Question Jerry rig Thunderbolt 3 to a laptop?

[justapotato]

So I've been learning up on ways to implement eGPUs, and looking into thunderbolt and the less popular m.2 method, and I was wondering: If PCIe x4 cards like this one (https://www.scan.co.uk/products/asu...sible-usb-31-type-c-and-displayport-12-pci-ex ) exist, and an M.2 M key slot is capable of acting as a PCIe x4, then should that PCIe card take an m.2 form factor, it would be possible to have a TB3 to M.2 input which would work in a laptop?

I'm asking this here so someone can call me out if I'm making some drastic assumptions or mistakes before I make a manufacturing request and look stupid af. I've found nearly every modern laptop has a spare M.2 slot, most of which are M key so that when users configure their laptops online they can pay a premium for NVMe storage cards. Considering this, most people without a TB3 have the possibility of getting one via this method.

 

[Math Geek]

so you are hoping to get/use some kind of adapter to convert this PCIE 3.0 x4 add-on card to work in an M.2 slot??

M.2 slots are usually x4 as well so i can see where you are coming from. no idea if it would work or if such a thing exists or can be made. but the basic idea does not seem totally crazy. i'm sure there will be some increased latency and speed loss associated with using such a thing.

as for making one yourself, there would be a lot of pins on both ends to layout and match and so on, but if you got the skill and access to all the specs for both slots, then you might have an interesting project on your hands.

one question is how do you plan on using it? since the M.2 slot will be inside the case and this thing will obviously have to sit outside the case. how will the cable run to it?

 

[justapotato]

I'm trying to get the attention of a manufacturer that already makes female pci x4 to male m.2 solutions and if that doesn't work maybe attempt to do it myself.

I intend to use a ribbon cable from the m.2 port ending with a type C female port, dremel out a hole in the case for it, and glue it into said hole. I made some quick reference imagery for the manufacturer I contacted: Solution idea and Mockup

 

[TJ Hooker]

One thing I've noticed is that all the TB3 add in cards I've seen require a TB3 header on the motherboard that they connect to, in addition to the PCIe 3.0 connection. Not sure exactly what the TB3 header is needed for though.

 

[justapotato]

You're right about the TB3 headers and that's had me stumped for a while, so I got to thinking how I could possibly work around that. I found this product on amazon (Link), which if I bought 2 of I could make a make a male to male m.2 solution to then plug into something like this (Link). That, in theory, would allow me to reverse the thunderbolt connection, as long as there's nothing built into TB3 that specifies which way a connection must be made. To be frank, I'm 80% certain there's a reason I can't do this, and that's why i'm putting it here to be shot down before I try