Question Black Screen after new CPU and Air Cooler

[butterflyfish]

Hi, I'm having a problem with a CPU upgrade. I replaced an i5 11400 CPU with an i9 10850K, and added a Thermalright Peerless Assassin 120 SE ARGB Air Cooler. I didn't have enough spots on the MB for both RGB connectors from the fans, if that's relevant. Both fans spin up, neither of them lights, no matter which fan's light is plugged in.
I didn't touch anything else.
Now I have a black screen on both monitors. No beeps.
I tried resetting the CMOS by removing the battery for 10 minutes.
I removed two of the four sticks of RAM and nothing changed.
Everything seems plugged in/connected securely.
What am I missing?

MB: B560 DS3H AC-Y1 (MB doesn't say y1, but Windows System did)
RAM: 4x8G DDR4 3200 MHz Chumwell Tech Ltd
Old CPU: i5 11400
New CPU: i9 10850K
GPU: RTX 3050
BIOS: F6 9/24/2021
Air Cooler: Thermalright Peerless Assassin 120 SE ARGB
Case: Rosewill Zircon I
Monitor 1: Acer SB240YBbix 23.8"
Monitor 2: Acer KC242Y Hbi 23.8"
PSU: 550 W Gold
OS: Win 11 Home
SSD: 512 GB
HD 1: 2T
HD 2: 4T

This is my first CPU upgrade, and I have no idea what went wrong. Everything was working fine before the upgrade attempt. The "new" CPU was a used one that was gifted to me, and was working previously. The HDs are either WD or Seagate. I forget which.

 

[Lutfij]

Welcome to the forums, newcomer!

If this is your motherboard;
https://www.gigabyte.com/us/Motherboard/B560-DS3H-AC-rev-10/support#support-cpu
you should be able to drop in the i9 10850K with the first BIOS release on the board.

Personally I wouldn't have gone with an K or an i9 processor with that board.

That being said, perhaps try and relieve some mounting pressure by unscrewing the mounting screws on the CPU's cooler, a couple of turns anti-clockwise.

PSU: 550 W Gold
What is the make and model of your PSU and it's age?

Inspect CPU's socket for any bent r broken pins.

 

[butterflyfish]

Not sure the make, as it came with the pc. But it's about two years old.

Oh, and the motherboard is Rev 1.2 sorry I forgot to say that