Windows Forum Admin
You want the top one, it's full speed when the chipset isn't. The M.2 on the chipset is shared with SSD ports. Top one is straight to the CPU.
I'm using the top m.2 is at pcie 3x4. My GPU is @16x so I'm afraid he is wrong. He is a great overclocker though.I'm going by the various reviews I saw. derBauer recommends use the lower m.2 slot, as the top one decreases the video card's speed tp x8.
Hard not to believe him, as he's one of the best known over-clocker's going today.