You can refer below link for riser combination where various GPGPU are supported [URL]  Below link have details on GPU enablement kit and parts needed for GPU configurations [URL]  Hope this helps
HI all, i need help,i woul like to add this GPU to PER740XD 8-bay,but i would like to know ,whitch risers i need ,power supplies, any extra cables for GPU ,any help is good ?   Thank you.
PER740XD GPU Dell NVIDIA A16 Passive GPU