4k/60

hi, i have an amd ryzen 9 9300x 4.5Ghz oc and a video card msi rtx 2070 super ventus oc 16 Gb, i opened 6 obs at the same time .. i started the stream, but no hardware encoder goes except 2 .. the other 4 have to start software encoder .. and my problem is that .. I can stream only one with 4k /...