new build not booting

i built a new pc the other day and can’t get it to work it’s using my original motherboard and ssd but everything else is new

i switched to my original cpu and through lots of trial and error found out i have two problems

1)when my new cpu is in the system doesn’t work but it has power running through i.e the fans are lit and spinning as well as the cpu cooler (it doesn’t have lights but spins) however my gpu doesn’t spin but the logo lights up but no visual on monitor from both motherboard and gpu

2)when my new nvme is in with my original cpu it gets to my motherboards logo screen with bios prompts but then goes unresponsive no more changes and my inputs stop working

i’ve totalled up my wattage across every part including fans and i still have 250 watts of headroom so i’m convinced it’s not power but perhaps a bios ? my motherboard is a asrock a320m and it had no info on bios version and said it was in legacy im just so stumped if you need any other info i’m more than happy to share i’m just at a dead end

thanks !!