SOLVED by @jj122@lemmings.world

Make sure all power connections on the mb are made (there are more than just the 24 pin).

I hadn’t connected the PSU CPU cable. Now it works: https://streamable.com/9bwg1k

Also thanks guys for suggesting the dual channel slots spacing between the memories.

Thanks everyone. You’re all wonderful.

See video https://streamable.com/agio65

PC SPECS:

• CPU: Intel Core i9-12900K
• iGPU: Intel UHD Graphics 770
• Motherboard: GIGABYTE B760M AORUS ELITE (manual)
• Power supply unit: Corsair CV 650
• Primary memory RAM: CORSAIR Vengeance 32GB DDR5 (2 x 16GB)
• Secondary memory SSD: Western Digital WD BLACK SN770 M.2 2280 1TB
• CPU Cooler: Cooler Master Hyper 212
• Case: Corsair 220T RGB
• Monitor: LG 24MK430H 24"
• Keybaord: Logitech K120 USB