X2100 / X210 Hack: Combine PCIe & SATA for PCIe 2x

[flyingfishfinger]

Hey,

EDIT: Blog post with details now up: https://rsend.wordpress.com/x2100-new-a ... -coreboot/

Quick note for fun, I'll write a blog post with more details this weekend but here's the gist:
It's possible to combine the upper PCIe port on the X210 or X2100 with the SATA port (in PCIe mode) to achieve a 2x PCIe port. This has significant speed advantages:

- Regular SATA HDD achieves ~550 MB / sec
- NVMe drive on the upper PCIe port (x1) achieves ~ 860 MB/sec

- NVMe drive on upper PCIe port combined with SATA in PCIe mode (= x2) achieves ~ 1550 MB / sec

I'm not sure what this is "worth" - we could have two SATA drives or one NVME drive with a custom adapter (which I'll probably build for fun) except that it achieves 3x the speed of a regular SATA drive - Is that noticeable speed improvement in regular use?

It's nowhere near the PCIE x4 throughput of an NVME drive in its dedicated slot of course, but it's a good improvement on a single SATA drive and would let us equip two separate NVME drives, for example.

Pic of test setup: