PCI Express riser

We have a project where we want to use a a 8-lane PCIe card with The Jetson TX1…

Does anyone have any experience with this, and could recomend a PCI Express riser or adapter?

Does the PCIe endpoint on your card have the ability to auto-negotiate down to x4? If so, a mechanical riser may work (although we haven’t tested). Here are some examples:

http://www.amazon.com/Express-PCI-E-Female-Riser-Cable/dp/B00CJE0KJ6
http://www.logicsupply.com/exp4-797-10/

The examples above with flexcable are more affordable, but may not offer high enough signal integrity for sustaining gen2 operation.
Here’s another example, integrated on a single PCB: http://www.amazon.com/StarTech-com-Express-Extension-Adapter-PEX4TO16R/dp/B004H5UKUE/ref=sr_1_11?ie=UTF8&qid=1458313885&sr=8-11&keywords=PCIe+x4+to+x16