problematiq :
laststop311 :
PROBLEMATIQ not all m2 slots are run thru the PCH. Some have their lanes directly connected to CPU. so there is no DMI latency or bandwidth problem.
M.2 use's 4 lanes of PCI-E. If you are using 16 lanes for a graphics card using say a 200 series board you are already using all the lanes direct to your CPU in which case it uses the 24 connected to your PCH.
https://en.wikipedia.org/wiki/Intel_X99#cite_ref-anandtech-8557_8-2