DIY "mPCIE to PCIe adapter" failure

[RokasK]

This is not a call for help, this is my story - I tried something new and did not succeed. I did not see anyone trying to solder a mPCIE adapter themselves, so this may very well be the first warning for future hobbyists. Also, this is a verification that Dell N7110 laptop (motherboard version DA0R03MB6E1) accepts an eGPU without any extra tinkering.

 

So I had the idea that a PE4C for 80$ is too expensive and I can make my own, since it's just a passive adapter - no transcoding required. So I bought these 3 things:

http://www.ebay.com/itm/Mini-PCI-E-to-PCI-E-Express-1X-Extension-Cord-Adapter-Card-with-USB-Riser-Card-/381392799818?hash=item58ccc8484a

http://www.ebay.com/itm/Flexible-Mini-PCI-Express-PCI-e-Card-Extender-52pin-M-to-Female-Extension-Cable-/151575020362?hash=item234a93434a

http://www.ebay.com/itm/1-5-3-5Ft-0-5-1-1-5m-HDMI-male-to-female-panel-mount-extension-AV-Cable-for-HDTV-/281348093974?var=&hash=item0

 

The idea was: 

1. cut the extension cable AND the hdmi cables in half

2. solder male extension cable part to female hdmi cable part (just the required PCIe connections and with as little distance between them)

3. Solder female extension cable part to male hdmi cable part

4. put step 2 results in my laptop with the hdmi female leading out the side

5, put step 3 results in a box, plug the cheap adapter into it, a video card into that

Done.

P.S. In Dell N7110 the mpcie is in an awkward spot. Was willing to desolder a VGA connection and use that chassis hole for the eGPU.

 

At first I tested if there is any functionality at all - took the extender, plugged it in my laptop, connected the adapter, the video card - success! Windows 10 recognized the video card, installed drivers, was able to play Fallout 4 on a laptop that had only Intel HD graphics and could not even launch the game before. Downside - only PCIe V1 speeds. I thought maybe it's due to the adapter being lame - contacted the seller, he repeated that it's only meant to work at V1 speeds. I had planed to use V2 speeds, so I made a new plan. Bought a PCIe extender:

Cut it in half. Now the plan was to modify step 3 by soldering the female part of this to the male part of the hdmi cable thus making IT the adapter.

Now came the time to find out which pins from the mPCIe to use. Did as much research as I could, cross-referencing with a discovered success story of extender to expresscard, reading the hw-tools schematics and anything I could think of. This was my last attempt (also, bought an arduino breadboard):

Yet still, the computer would not recognize the video card. There was some reaction - when the video card is powered, the fans spin at max speed, but when I power on my laptop (with this connected), the fans slow down to minimal speed. At this time after a few months of work my motivation ran dry and I gave up. The last thing I found was a mention that the data transfer cables not only go in pairs, but also there must be a strict value of resistance between them, or through them... (https://boundarydevices.com/wp-content/uploads/2014/12/PM2-C.pdf) That was it, I did what I had energy for and it was time to call it quits. Now I am selling all the remaining parts

 

Also, I add my notes here in "Open Document" format for those who would wish to succeed me:

kontaktai.7z

[Another Tech Inferno Fan]

Are you sure you're even supposed to have those two ribbon cables connected to a breadboard like that?

 

There is a small parasitic capacitance between the rows on such breadboards , and may cause high-frequency signals such as those in PCIe to mix in with each other between the rows.

 

 

Edited May 7, 2016 by Arbystrider

[Khenglish]

Yeah you can't use a breadboard for anything higher than a few MHz. Breadboard connections are too poor. You need well soldered connections for 5GHz.

[RokasK]

Soooo... next testing step would have been to keep everything as it is (the breadboard) except pull out the TX, RX and clock pairs and solder them together. As memory serves me, there are no other information channels.

[TechnoHD]

How do you wana speed up the Adapter? 

[DaCM]

And now you know why the PE4C costs this much

[TechnoHD]

Do you talking with me? or with RokasK? And on the the PE4C V3.0 i cant see any chip or IC wich will make out of the one pcie lane in mpcie 16

 

 

Edited September 22, 2016 by TechnoHD

[Sgt Chaos66]

I'm interested in replicating the Male mPCIE adaptor to female HDMI cable as I would like to modify my case to just have a female hdmi to connect to my beast.  (Small Male to Male) 

 

How difficult is it to solder mPCIE to HDMI?  I've tried searching but my search parameters are too vague. 

 

Wpuld aprreciate ate anyones thoughts.

 

Thanks,

 

Stu

[RokasK]

The mpcie pins are very tiny, so you need a very small soldering iron and steady hands. You also need to check with a multimeter which pcie pin on the beast transfers to which pin of the hdmi cable - it will be several pins to one cable, so don't stop at the first. That's sort of it