Question - Which Slot to use?

Certain desktop PC peripherals like wi-fi cards can come in the form factor, but the most common use for is SSD data storage, basically

Using first slot M2_1 makes my PCIe x16 lane go to x8 I prefer drive performance over video as I do more work than gaming Not sure if it's

which interview slot is best And heres all info on the : SSD5, 80mm,SATA III,540s Series,480GB All this is very confusing to me,and I`m sorry if I seem difficult In the motherboard

which caliper is used to measure the width of the slot Certain desktop PC peripherals like wi-fi cards can come in the form factor, but the most common use for is SSD data storage, basically