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.