It's PCIe 2.0 - x1 for the miniPCIe, and the x16 slot is really an x4...I ask the sellers if the t620 has a mSATA and if not:
I will put the HDD outside the case and want to use a mSATA to SATA adapter:
Would be nice to know what revision the mini PCIe has and how many lane's.
What are you planning to do with it (that would require a 6-8TB drive hanging off the side)?
You sure you don't want to consider something like an 80 dollar HP 290 instead?