Sorry. A bit confused on your comment.
“So i guess a old dualcore cpu with a gpu on this state will not enough?”
If you mean the Raspberry Pi, no.
If you are talking about a older computer, post the specs, it will allow me to more effectively judge it. A dualcore should be plenty for just a simple capture card (with some other possible inputs) to stream encoding, especially if it has a dedicated GPU, but again, it would take knowing the exact hardware to rate it. But like I said, even if that computer isn’t exactly a streaming PC, there are other things you can use that to improve your streaming PC performance.