Black screen after new cpu

[HammerdCow]

I ha e no idea if this is the right community but I’m new here and really need help I have an existing build running windows 10 with a Rog b450-f and a Ryen 7 2700x and my friends grouped together to buy a new cpu for me they said they checked that it should work with a bios update it’s a ryzen 75800x and I have updated the bios but whenever I put the new cup In it gets to the bios but when I continue it just black screens.   I really need help with this my next option is taking it to the local tech guy in Wimbledon as I’m not experienced enough for this

Edited October 17, 2021 by HammerdCow

[Forleb]

Have you tried putting the 2700X back in, or do you no longer have it? Does anything connected to the motherboard look like It's receiving power?

[Dr0idGh0sT]

Does it black screen in wondows? If yes, try to reinstall windows.

[HammerdCow]

3 hours ago, Forleb said:

Have you tried putting the 2700X back in, or do you no longer have it? Does anything connected to the motherboard look like It's receiving power?

It runs perfect with the old cpu I don’t know if I was given a dead one or wether it’s a software thing

[Forleb]

13 hours ago, HammerdCow said:

It runs perfect with the old cpu I don’t know if I was given a dead one or wether it’s a software thing

That's a good start, it means you didn't brick the board during the bios flash. You could try clearing CMOS and flashing bios again to be certain something isn't manually preventing this to work in your settings. Beyond that, there's always a possibility your 5800X is defective, but the fact that you can get into bios with it makes me believe that the route of CMOS > flash > retry will succeed.