As I have been building rigs for a few years now, I could see by installing the riser cable adaptors they were not secured in any way shape or form, this can very easily damage your system, destroys GPU's.
So I designed a retaining clip, I called RiserSafe, its fits all boards with the edge lip on the PCIE plug on motherboards.
Once in place its locked and you can pull on the cable/adaptor and they will not come out.
You may say yours don't move, well if your rig is bumped, moved or you put your hand in there to move/change a cable or part, the idea is you install the cheap clip and then you can't damage your expensive rig.
Here is a link to what it is.http://www.miningcryptocurrency.com.au/risersafe.html
They are also sold in the store as well on that site.
I have been selling these world wide ( postage costs are more than the clips unfortunately ) but still a hell of a lot cheaper than destroying hardware.
Hope this is of help.