@Thomas miao 

Before trying additional driver changes, please first determine whether the problem is specific to Windows or also occurs outside the operating system.

Disconnect all docks, USB devices, external monitors, and other peripherals. Connect only the original Dell AC adapter.

Press F12 → Diagnostics and run the extended memory and system tests. Please record any exact error code and validation code.

Enter the BIOS with F2 and leave the system there for 15–30 minutes. If the problem also occurs in the BIOS, it is unlikely to be caused by Windows or a normal Windows driver.

If possible, boot from a Linux live USB. This is a useful way to compare the system independently of the installed Windows image.

For overheating or fan-related symptoms, monitor the CPU temperature, clock speed, and thermal-throttling status with HWiNFO. A high fan speed does not always mean the cooling system is defective; it is important to check whether the CPU is actually throttling.

Test the system once with the internal battery disconnected and the original AC adapter connected. Also test without any USB-C dock or third-party charger. A defective battery, charger, or dock can cause charging problems, shutdowns, throttling, and instability.

Inspect the cooling system physically for blocked vents, dust, a loose heatsink, damaged fan cable, worn fan bearings, or incorrectly applied thermal compound.

If the system freezes, crashes, or restarts, test each RAM module separately and check the NVMe SSD health and SMART information. Intermittent memory or storage errors can produce several apparently unrelated symptoms.

If the issue occurs only in Windows, perform a clean boot and check Event Viewer → Windows Logs → System for WHEA-Logger, Kernel-Power, ACPI, Display, and Thermal-Framework errors.

Please provide the BIOS version, Windows version, exact symptoms, charger wattage, dock model if applicable, and the F12 diagnostic results. This information should help determine whether the cause is Windows software, thermal behavior, power delivery, memory, storage, or a system-board/display hardware fault.

I hope this helps! If this was useful, please hit 'Yes' or 'Like'! Thanks! 😊

Hi

Something, historically, I have experienced...

Important: If Windows is already installed while the system was in RAID mode, switching to AHCI without preparing Windows can cause a boot failure.

For a clean install or new drive, just install with AHCI selected. If you must switch modes on an existing Windows install, you’ll need to prepare Windows for the driver change or do a fresh OS install.

With Windows 10 machines, dual booting with Linux.

These four words are the place to start:

"hottest in the world"

This is a 2019 model -- at 7 years old, has it had internal cleaning and replacement of the thermal pads?

If not, that's long overdue.

Along with the CPU and GPU, SSDs will throttle if they are running overly hot.

@ejn63​ I have regularly open the back cover to clean the cpu and gpu fan. the huge volume heat running out from the left vent outlet. it means the fan works hard to drive out the heat. currently I have to let it sitting on the logitech N100 cooling pad. I have also order Honeywell- PTM7950 Thermal Pad to verify it will work or not. thnks alot.

@Sharan G​ thanks for your advices, the real issue is the latest bios version 1.44 released end of last year cannot be modifed and bios will die once you change the default setting. and you are not allow to roll back to previous version. there were other issues such as the mouse and touch pad will freeze suddenly after runnning 10 to 30 minutes and you have to force to press power butten to turn the laptop off. it is strange that previously this laptopt never all to install dell supportassistant app and now it is OK to load supportassistant and I run this app 3 times to let the laptop to update automatically to the latest drivers. thanks, Thomas

@anne_droid​ thanks for your advice, the real proplem is that the latest bios 1.44 version not allowing to change from default RAID on mode to AHCI mode, if doing so, the bios will die. I have to reinstall the win 11 at RAID mode again. I asked google ai and I was told that the previous 1 tb HY nvme pcie M2 is not good and I replace it with different type GeIL P4a 2 TB. the big difference is if I use laptop 15 years ago with normal sata ssd, it boot to windows 10 with 15-20 seconds， this dell latitude 5401 take over 2 minutes. I ask google again that I was told the latest bios faild or takes time to communicate with your M2 drive and it was problem of BIOS.

the following is the soluton from Google AI and if the latest not die when changing the Raid on mode to AHCI mode. It may solve the long booting time。

Dell Latitude 5401 suffers from severe firmware and driver-level bugs when clean-installing Windows 11 on certain aftermarket M.2 NVMe SSDs.

Community members frequently encounter a bug where the system gets stuck in a multi-minute boot loop or hardware timeout due to Intel Rapid Storage Technology (RST) conflicts or an unstable Realtek PCIe Card Reader driver trying to initialize during startup.

The exact, verified solutions sourced from community replies to fix this specific issue include:

1. The "Realtek Card Reader" Driver Disabled Fix

A notorious bug on the Latitude 5401 causes the clean Windows 11 installer to apply a generic Realtek driver that hangs during the boot cycle, adding up to 2.5 minutes to startup.

• The Test: Go into your Device Manager (right-click the Start button), expand Memory technology devices, right-click the Realtek Card Reader, and select Disable device.
• The Result: Restart your PC. If your boot time immediately drops to under 20 seconds, this driver was the culprit. You can either leave it disabled or install the official driver directly from the Dell Support.

2. Force Windows from RAID On to AHCI Mode

Most Dell systems ship with the storage controller configured to RAID On, forcing Windows to route the NVMe traffic through the Intel RST framework. Switching to native AHCI bypasses this problematic layer. Because changing this setting normally causes a Blue Screen error, you must use this specific trick to do it safely:

1. In Windows, click the Start menu, type cmd, right-click Command Prompt, and choose Run as administrator.
2. Type this exact command and press Enter: bcdedit /set {current} safeboot minimal
3. Restart your laptop and repeatedly tap F2 to enter the BIOS.
4. Go to System Configuration > SATA Operation (or Storage) and change it from RAID On to AHCI.
5. Save changes and exit. Windows will boot automatically into Safe Mode.
6. Open Command Prompt as administrator again and type: bcdedit /deletevalue {current} safeboot
7. Restart one final time. Windows will boot normally using the optimized native NVMe driver.

Hi

Boot into Safe Mode (Critical for Windows)
If you already have Windows installed, switching to AHCI directly may cause a "Blue Screen of Death" or boot loop because Windows lacks the AHCI driver in standard boot mode.

1. If the system boots into Windows normally, skip to Step 4.

2. If it fails to boot, force three failed boot attempts to trigger the Automatic Repair screen. 

3. Select Advanced options > Troubleshoot > Advanced options > Startup Settings > Restart. 

4. Press 4 or F4 to enable Safe Mode. 

Step 4: Finalize and Reboot

1. Once in Safe Mode, Windows will automatically install the necessary storage drivers.

2. Restart the computer normally. The system should now boot quickly in AHCI mode. 

Alternative: Full CMOS Reset
If the setting reverts to RAID automatically after reboot, perform a hardware reset:

• Power off and unplug the AC adapter.

• Hold the power button for 30 seconds.

• If possible, open the back cover and remove the CMOS battery for a few minutes before reassembling.  This clears the corrupted BIOS state causing the random RAID switch.