[NAME] The Setup and specifications say "Two M.2 2230/2280 slots for solid-state drives", so both 2230 and 2280. There are two PCIe x4 slots (SLOT1 & SLOT4), if the PCIe card is in SLOT1 it would be above the M.2 slot, not a problem unless the M.2 in that slot is higher than normal. If the PCIe card is in SLOT 4 there does not appear to be anything that should cause a problem.   
Hello, What is the form of the M.2 that ships with the XPS 8950? Is it a 2230 or a 2280? If it's a 2230, can the first slot take a 2280? It's not clear from the manual since it uses a 2230 as its example. Assuming it's a 2280, how much space is available for the a PCIe card next to it. I was hoping to add a 10G network card, but I was wondering how much space was available. Thanks in advance!  
XPS 8950, included M.2 SSD, PCIe space