What is the advantage of the adapter?

[n3de]

Hey,

first of all, thank you very much for the products! I bought zwo Dual Edge TPUs and did not mention, that they use E Key. My first question is, why? Why did they use E Key and not M Key for the Dual Edge TPU?

I have a Gigabyte MW34-SP0 https://www.gigabyte.com/de/Enterprise/Server-Motherboard/MW34-SP0-rev-10#Overview

I can only use one Dual Edge TPU and I'm not sure if both tpus will be recognized. So I ordert two adapters befor I found your solution: https://www.delock.de/produkt/65831/merkmale.html?f=s

I will buy your PCIe Adapter for two Dual edge TPUs, but I want to understand what is the advantage of your adapter compared to the delock adapter?

Edit: Can I use the Low profile PCIe x4 Card with the PCIe x16 slot? So the TPUs will be directly conneted to the cpu :-)

[magic-blue-smoke]

Hi @n3de Congratulations on Dual TPU Cards purchase. Seriously, I'm waiting for mine since August last year :)

Each PCIe/NVMe slot has only one PCIe port, but one to 16 lanes. Dual TPU Card has two identical TPUs and each TPU has its own PCIe interface. It's like two independent devices sharing the same PCB. This means Dual Edge TPU requires two PCIe buses and the only slot that offers this option is m.2 E-key (implemented to the full specs). Most manufacturers give up with second PCIe bus, also some E-key slots have no PCIe at all

Diagram you're showing demonstrates there's only one PCIe interface for E-key slot. M-key slots are also have one PCIe bus. This is why you can see only one TPU per slot

DeLock adaper passively routes power and data pins from M- to E-key. This would work great to install WiFi card to M-key slot, but only one TPU will be detected with this adapter

My adapters have active PCIe switch (treat it like USB hub/port replicator) and provide several PCIe buses out of one. There's little more on this at the bottom of README.md

Edit: Can I use the Low profile PCIe x4 Card with the PCIe x16 slot? So the TPUs will be directly conneted to the cpu :-)

Yes, PCIe interface allows to use less lanes than there's on the bus. And this is exactly what I have in my test system. Note that as of today PCIe x4 to two Dual Edge TPU cards adapter only exists as working prototype with no exact release date. However, if you feel enthusiastic about testing it, drop me a message using a contact form at the bottom of page here

[n3de]

Hey @magic-blue-smoke,

thank you for the explanation. I read the readme, but I understand the sentence "Only A- and E- key m.2 slots implemented to a full specification have two busses." now.

How das the switch influence the performance at the PCIe card for two Dual TPUs and the dual TPU adapter? Have you a comparison between a single TPU and a Dual TPU with your adapter. That would be interesting.

I will send you a mail regarding the TPUs and the testing.