OBS does not need a strong graphics card, but will perform significantly better with one. We use an Nvidia graphics card with Turing NVENC such as the GTX 1660 Super on a low budget computer. When I say "low budget" I mean the graphics card cost more than the rest of the computer.
I have experimented with an i7-4770k CPU, and an older i5 processor with GTX 1660 Super GPU, and the latter produces far better video quality with better performance (under 10% CPU usage). I ended up installing a graphics card in my machine with the 4770k so I would have one there too.
With that said, the first machine I ever ran OBS on was a laptop with an i5-4210 and no usable hardware video encoder. I used it for three and a half years until my employer could afford something better.
