Hi There
I am in the same boat. Same symptoms.
9950X3D.
MSI Tomahawk x870
MSI 1000Watt PSU,
Mushkin Vortex SSD.
Trident Z5 F5-6000J2636G32GX2.
Nvidia 4090.
Retailer "stress tested" the CPU for me and found no issues for a RMA.
This is a soft freeze, keyboard lights still work, and the Debug LED's still cycle through the CPU temp changes.
New Windows 11 24h2 fresh install stuck on searching for discs etc.
Ubuntu runs fine, as well as booting from a memtest flasdrive 4 lapses, no errors.
Disabling Secure Boot, Disabling C States, Disabling USB AHCI.
I then managed to work through a few of the freezes using Windows 11 23h2 install. eventually got everything up and running. Revo cleaner to remove MSI chipset drivers, and loaded x870 chipset drivers only from the AMD driver page. Gaming last night and everything went fine, just some CPU parking issues.
Shutdown/reboots still freezes in Windows 11 23h2.
Safe Mode works fine with no freezes.
As soon as I go into device manager and scan for new devices, or do something related to suspend/sleep etc, it freezes again. so it could be more a AHCI / ACPI issue? (removing all ACPI and AHCI devices in safe mode gets me a booting windows again)
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Tried upgrading and fresh installing to Win11 24h2 today, now I'm back to square 1 lol.
Things that I tested , which didn't make a difference from other suggestions on forums:
-Bought a new motherboard, same model, to rule out any faulty pin's or peripheral issues.
-Expo on/off
-PBO On/off
-Only using 1 RAM Module, different slots etc.
-Tried a different SATA SSD, or a Samsung EVO SSD for Windows
-Testing with Kingston Fury RAM
-Different USB drive for Windows Install
-Clear CMOS using the reset buttons
MSI Support also provided an alpha Bios file newer than the support site, same issue.
Using a 8800G AMD CPU in this setup works fine, no issues.
Going to retry the Win11 23h2 for now, using power button every time the install freezes to get a working Windows again.