This power supply already offers - 4pin 12V + 8pin 12V or - 8pin 12V + 8pin 12V https://www.bequiet.com/admin/ImageServer.php?ID=4c941a40140@be-quiet.net&rand=28b9d0168c2e2e47a7fd3932bef82e27&lang=2&force=true&download=true&omitPreview=true A second or third 8pin 12V? What kind of mainboard is this? On the bequiet website, the matching cables are listed under accessories.

Do you even need the ATX 4 pin? Normally, the 8pin 12V_1 is sufficient. This is also mentioned in the manual.

On the mainboard side they are quite standardised, but on the PSU side they are very proprietary. So it only fits current be quiet! PSUs that have this strange 10-pin outlet. I fell for it and had to return it. :D