Practically nothing on the high seas. But this is L1T, and someone’s probably tried something crazy. 
I’m tempted to get an Adaptec HBA Ultra 1200-32i to see if it works with the cable I still have for the super special Optanes. I was never able to get the Broadcom P411W-32P to bifurcate its lanes down to x2x2x2x2, but the Adaptec HBA has a software utility to dictate how many lanes per port.