good post Bro. As an electronic tech for 40+ years and learning to solder when I was about 8 (56 now) I have seen so many solder / production problems. Nowadays almost all cards and boards are wave soldered, and I can tell you as a tech that used to babysit these machines it is a pain to get them running the way YOU, and all of us would like to see. As you recommend, LOOK at your boards ! you can see where there is sloppy work, take your time and FIX them, (it's really not hard to learn to solder) before applying power. But hey, it's your money ... just a thought.
Read More, Reason More ... JTS
The PCI-E riser boards are usually soldered by hand in China and while there are some with really good solering, there are others with crappy one and then there are the ones with the solder leaking and shorting multiple connections. Then these boards apparently do not go through any quality control and get shipped to customers... not the way to do things properly, but some of the miners ar also to blame as they are looking to save cost from everything and go to the cheapest option.
I've been one of those miners before. Was too focused on that initial ROI, being as cheap as possible.
I learned my less and pay a little more for quality. Always worth double-checking too, I watched someone repair my phone in Hong Kong once, and saw that he forgot to put the battery back in before gluing it together. Accidents happen and with these super-cheap no-QC products, you're asking for trouble.