How can I make NT powerdown on shutdown?

A. Follow the procedures below:

  1. Start the registry editor (REGEDIT.EXE)
  2. Goto the Key HKEY_LOCAL_MACHINE\Software\Microsoft\Windows NT\CurrentVersion\Winlogon
  3. If the value PowerdownAfterShutdown exists change it to1. Go to step 5
  4. If the value does not exist add it as type REG_SZ and set to 1
  5. Exit the registry editor

You will need an ATX power supply and an updated HAL.DLL from the computer manufacturer in order for this to work, otherwise the machine will just reboot.

Windows NT 4.0 Service Pack 4 and above ships with a file, HAL.DLL.SOFTEX which works on many systems. 

To obtain the hal.dll.softex (and halmps.dll.softex for multi processorsystems) run the service pack executable of the service pack you actually have installed with the command line parameter /X . This will extract all the files in the service pack to a temporary directory without installing them. You'll find hal.dll.softex and halmps.dll.softex among the extracted files.

To install perform the following:

C:\> cd %systemroot%\system32
C:\WINNT\system32> rename hal.dll hal.old
C:\WINNT\system32> copy g:\i386\hal.dll.softex hal.dll


An alternative to renaming hal.dll would be to add option /hal=filename.ext in "boot.ini".

Another file, halmps.dll.softex, is shipped for multi processor systems. Some people have reported that after using the softex dll's the CPU miss the idle loop's and this stay at higher temperatures so you may want to watch out for this.  If you purchase Softex NT Power Management v2.19 and install it the same happens on a Dell Inspiron 3500 Laptop with Mobile Celeron 366.

Softex have a newer version of the HAL.DLL version 4.0.1381.5 which fixes the CPU idle problem. You can download this from I believe.

Windows 2000 includes better support for ACPI.

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