I’ve been dealing with this nightmare for weeks and really need help.

My previous motherboard and ram sticks had to be RMA’d so I replaced my motherboard, ram and my psu (I suspected the other one wasn’t doing too great after 6 years) I am also reinstalling windows 11

My problems are:
1: BOOT LED gets stuck on startup, no signal to monitor, no keyboard response. Sometimes resolves after CMOS reset, sometimes just takes multiple attempts.
2. BIOS randomly freezes, sometimes mid-navigation, sometimes right after opening.
3. Windows 11 installation freezes at random percentages (6%, 10%, 23%) every single time. Spinner stops, nothing happens, have to hard shutdown.

What I’ve tried:

•   Multiple CMOS resets  
•   Disabling Fast Boot  
•   Enabling/disabling CSM  
•   Disabling Global C-State  
•   Booting from both USB and UEFI USB options  
•   Disconnecting all drives except install target  
•   Only 2 RAM sticks in A2/B2  
•   Checked CPU temp — 41°C, fine

These are my specs:

CPU: AMD Ryzen 7 9800X3D
• Motherboard: ASRock X870 Pro RS (brand new replacement, previous one RMA’d)
• RAM: 32GB Corsair Vengeance RGB DDR5 6000MHz (2x16GB in slots A2/B2, other 2 sticks removed for testing)
• GPU: Gigabyte RTX 4070 Windforce 12GB
• PSU: Cooler Master MWE Gold 850W (new)
• Boot drive: Samsung 860 EVO 1TB SATA SSD
• Also installed: Samsung 970 EVO 500GB M.2, Samsung 980 PRO 2TB M.2 (disconnected during install attempts)

Any help would be appreciated because I’m losing my mind and not willing to spend €65 an hour to go to a computershop.