This was covered not that long ago in another thread. Solutions: wrapping various kinds of tape around the connector, suspending the cable with various kinds of thread or line, propping up the cable with various home-made contraptions--I remember one which was a cradle made out of Lego bricks. It's a fact of life that there will slight variations in the standard: I've experienced both connectors that it was virtually impossible to get into the socket, and connectors that were loose. The weight of many high-end PCs doesn't help!
Power cable connection issue, plug slightly sags and disconnects
heavier Power cables tend to not fit very securely so if there is a slight connection angle they no longer carry the power. How are you supposed to maintain a horizontal connection when they are so heavy???
Slight movement to a rack tends to cause the disconnection.
So I go back to the cheaper, much cheaper, much lighter and flexible power cord received with device and it fits really good.