There are 3 variations of Riser 1 for the Dell PowerEdge R740. This variation is the shortest riser and allows for installation of a mini RAID controller. Longer variations take up the slot as explained in this post.
This particular riser has 3 x8 slots. It lacks a x16 so keep that in mind.
This is the riser for the HP DL 325 G10. One slot is x8 the other is x16.
This is Riser 1 compatible with both R730 and R730xd chassis.
Installation:
This is the x16 half riser compatible with the R740xd chassis. It is typically used in tandem with a rear flex bay. Because the rear flex bay requires the removal of risers 2 and 3, the low profile half riser is able to sit beneath the flex bay for an additional x16 slot.