the maker sells many cards, 620 is basic and will never run faster than the pci-e x1 socket.
Read the spec on x1, for reason.
the reason above poster has issues, is your dirty bit is failing when windows shuts dow,n the last thing
it does is set the dirty bit in the pagefile.sys. at shut down,. then on reboot, if it is true (dirty) you get , that message (illegal shut down)
that fact will put you on the right track.
WD bundles this card with some HDD.
dont expect blinding speed.
unless
1: old mobo bios cant do sata 2 or 3
2: old mobo has on sata at all.
3: old mobo, like me has the nforce bug, where it can not speed shift to lower sata speeds. nforce560
if you expect this card to upgrade new mobo's you are sadly mistaken, that is not its purpose.
if doing raid, see the 640s etc. (im reading all SSD posts)