Yes, I would agree that riser cards (and their cables) have a much higher failure rate (or are doa to begin with) then any of the other components in a typical mining rig. We try to order an extra 20-25% for our past few orders of them and only buy the good ones from reputable places (if you can find them in stock).
Could not agree more. I am building these systems for a client and ordered an extra 5 of them.....Yeah RIG two looks like it will end up using 3 of these new backup ones and I still have two more 6 gpu systems left lol. I believe it was the owner or just an employee of miningrigs mentioned they had some models in the past that had as high as a 50% failure rate! Man I just wish we could get some reliable ones.
I am an experienced System Builder (SI or whatever the acronym someone is used to) and boy troubleshooting takes time. I dont know how someone doing this without or with little system experience handles this.