Regarding solder and ASIC PCB power pins:
Go big(with iron wattage and iron tip) or stay home.
And I brought big iron to the game, plus preheat PCB.
One of my PCIe connector 12V pins was not soldered well originally. fact.
(many in fact did not flow to top of PCB along pin, do they scrimp on Silver too?)
That's also my experience: the solder on the PCIe connectors doesn't melt well (or not at all)... the first additional plug I soldered on the backside of the board, just melted the plastic of the plug itself while the original PCB-solder was still hard... I had to plug in a PCI-cable into the plug first, to function as a heat sink. This worked more or less, but still wonder how well (or bad) the solder joined...maybe I need to redo it with a bigger Iron? What wattage did you use?