Mat in the hat

@Crunchy Dragon iirc linus did say in a different video (at freegeek) that he should have used some kind of a cable to link both

Most likely.

THANK YOU SO MUCH, I've never had an account :') I've only lurked! You people are super helpful and informational!.

Glad we could be of help, and welcome to the forums!

THANK YOU SO MUCH, I've never had an account :') I've only lurked! You people are super helpful and informational!.

Yeah, otherwise you have to find some way to trip the second PSU to turn on. The adapter is way easier to deal with

I did something similar with my brother's 780 lol, it works and it was a little funny too because I was running both our systems off our PSUs combined. The 6+2 pins from the 650 watt PSU and the 6 pin from the 500 watt will combine effectively. As long as both power supplies are switched on so all the power is delivered, you're good.
(and don't forget, use @skiwee29, although mine won't turn orange for some reason)

Austin Evans did something very similar to this in that one season of Scrapyard Wars he was in.

What are the make and model of these power supplies?
Is that in total or just on one PCIe power cable? I use a dual 6 pin to 8 pin if this happens to me.

Power is power, it wont care where its coming from, as long as its getting the proper power. So yes, in theory, your plan should work.