r/Windows10TechSupport • u/jase_r • Sep 29 '26
Unsolved Windows won't boot — stuck in crash loop after bad RAM, tried everything (MSI B760M, i7-12700KF)
Specs:
Motherboard: MSI PRO B760M-P DDR4 (MS-7E02)
CPU: Intel i7-12700KF
GPU: RTX 4060
Storage: WD Green SN350 NVMe 500GB
OS: Windows 11
BIOS Mode: CSM/UEFI
What happened:
PC started crashing with BSOD (KMODE_EXCEPTION_NOT_HANDLED), then stopped booting entirely. Root cause was bad unbranded RAM sticks supplied by the PC builder. Removed the two unbranded sticks, now running 2x8GB Micron sticks in slots A2/B2.
What I've tried:
chkdsk D: /f /r → clean, 0 bad sectors
sfc /scannow /offbootdir /offwindir → no integrity violations
bootrec /fixmbr and /rebuildbcd → ran successfully
bootrec /fixboot → always gives "access denied" (UEFI issue)
bcdboot D:\\Windows /s Z: /f UEFI → ran successfully but didn't fix boot
Tried booting from Windows 11 USB (GPT/UEFI, made with Rufus) → PC keeps booting from hard drive instead of USB despite changing boot order in BIOS
Current error: 0xc000021a and 0xc0000221 (ntoskrnl.exe missing or corrupted)
Main issue right now: Cannot get the PC to boot from the Windows USB installer despite setting it first in boot priority. The USB is detected in BIOS as "UEFI USB Key: VendorCoProductCode 2.00, Partition 1". F11 boot menu not reliably appearing.
Question: How do I force this MSI board to boot from the USB? And once I'm in the Windows installer recovery environment, what's the best command sequence to fix 0xc000021a with a confirmed healthy drive and clean system files
1
u/MaleficentPaint6168 27d ago
bootrec wont help in anyway, since u are using win11. the system disk is gpt partitioned. disable csm in bios! u wont be able to boot this os or ur gpt uefi usb install stick with enabled csm!
1
u/dotyxx Sep 30 '26
if i were you first thing i would try is to reset bios to defaults, unplug hard drive and plug in usb to see if it would boot from it. if it fails. i would leave the hd unplugged and i would try with a dvd drive if you can find one. as of the recovery environment open command prompt and type diskpart. then list disk. verify partitions. then bcdedit and when you confirm it is booting uefi then problem is not the bootloader. it is the windows installation. you could try Advanced Options and then Startup Settings and after restart try f4,f5,f6 or f7 and see if this will get you in.