On Fri, Dec 06, 2019 at 08:50:46AM -0500, D. Hugh Redelmeier via talk wrote:
<https://allpinouts.org/pinouts/connectors/power_supply/pci-express-pcie-6pin-power/> <https://allpinouts.org/pinouts/connectors/power_supply/pci-express-pcie-8pin-power/>
Or better (but look way down, from "6 Pin PCI Express (PCIe) Power Cable Connector" on):
<https://www.moddiy.com/pages/Power-Supply-Connectors-and-Pinouts.html>
The original 6 pins are all assigned 12v or ground. The extra pins in the 8 pin connector are just grounds. All seem to be connected.
Why two more grounds? Because the 8-pin is supposted to supply more power and "they" added pins to make this new requirement unmistakable. Or maybe they just actually needed two more grounds.
You said one pin on your connector was absent. => your connector isn't right
I don't know if this matters for your new card. Clearly it does not matter for your old cards. Is the pin missing for each of the connectors used for the old video card?
On the 6pin PCIe power, 2 are 12V, 2 are GND, one is sense, and one is either not connected or 12V (on the 8pin version that one becomes the 3rd 12V). The 8pin adds a second sense pin and an extra ground and makes the optional 12V pin required. The sense pins are connected to ground but are not to be used as ground wires. They are only for detecting that the cable is connected and what type of cable it is. -- Len Sorensen