If your powerpack only has one 8pin connector you can get a molex like the one in the picture below, also just make sure the power pack can deliver the exact watts needed for the GPU and motherboard to run perfectly
Yes I know I can do that but I don't think it's necessary. I think the extra 8 pin was just in case kind of thing to cover themselves legally. Every connector is a point of failure so I prefer to minimise them as much as possible. The question remains, is the card hardwired not to work without power supplied to both connectors?
Be aware that if you card would reset itself to default it will consume a lot more power than during mining. This could be problem, you could even burn 1x8 pin plug.
3060 has moderated consuption, but still... you can get very cheap converters, do not risk it.
No risk here. The 8pin can handle 150 watts. The riser supplies 75 watts. TDP of the card is 225 watts. In 3 years of continuous 24/7 mining I have never had any of my 24 cards "reset" such that they started using 100% of their rated power. I use afterburner to set the power limit and I've never had any problem. But even at worst case, a single 8 pin together with the riser is exactly enough to power the card. But no safety buffer.
The only problem I have had is connectors burning out. They are the weak point so I prefer as much as possible to minimise them.